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* rcu: Increase RCU CPU stall timeouts if PROVE_RCUPaul E. McKenney2010-03-11
| | | | | | | | | | | | | | | | | | | | CONFIG_PROVE_RCU imposes additional overhead on the kernel, so increase the RCU CPU stall timeouts in an attempt to allow for this effect. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1267830207-9474-2-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* ftrace: Replace read_barrier_depends() with rcu_dereference_raw()Paul E. McKenney2010-03-11
| | | | | | | | | | | | | | | | | | | | | | | | | Replace the calls to read_barrier_depends() in ftrace_list_func() with rcu_dereference_raw() to improve readability. The reason that we use rcu_dereference_raw() here is that removed entries are never freed, instead they are simply leaked. This is one of a very few cases where use of rcu_dereference_raw() is the long-term right answer. And I don't yet know of any others. ;-) Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1267830207-9474-1-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* rcu: Suppress RCU lockdep warnings during early bootPaul E. McKenney2010-03-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | RCU is used during very early boot, before RCU and lockdep have been initialized. So make the underlying primitives (rcu_read_lock_held(), rcu_read_lock_bh_held(), rcu_read_lock_sched_held(), and rcu_dereference_check()) check for early boot via the rcu_scheduler_active flag. This will suppress false positives. Also introduce a debug_lockdep_rcu_enabled() static inline helper function, which tags the CONTINUE_PROVE_RCU case as likely(), as suggested by Ingo Molnar. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1267631219-8713-2-git-send-email-paulmck@linux.vnet.ibm.com> [ v2: removed incomplete debug_lockdep_rcu_update() bits ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
* rcu, ftrace: Fix RCU lockdep splat in ftrace_perf_buf_prepare()Paul E. McKenney2010-03-04
| | | | | | | | | | | | | | | | | | | | | Change the pair of rcu_dereference() calls in ftrace_perf_buf_prepare() to rcu_dereference_sched(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <1267667418-32233-3-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* rcu: Suppress __mpol_dup() false positive from RCU lockdepPaul E. McKenney2010-03-04
| | | | | | | | | | | | | | | | | | | | | | | | | Common code is used during task creation and after the task has started running. RCU protection is not needed during task creation because no other CPU has access to the under-construction task. Provide the RCU protection anyway to suppress the false positive, as there does not appear to be a good way for the common code to recognize that the task is only accessible to the CPU creating it. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1267667418-32233-2-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* rcu: Make rcu_read_lock_sched_held() handle !PREEMPTPaul E. McKenney2010-03-04
| | | | | | | | | | | | | | | | | | | | | The rcu_read_lock_sched_held() needs to unconditionally return the value "1" in a !PREEMPT kernel, because under !PREEMPT, -all- kernel code is implicitly preempt-disabled. This patch makes this happen. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1267667418-32233-1-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* rcu: Add control variables to lockdep_rcu_dereference() diagnosticsPaul E. McKenney2010-03-04
| | | | | | | | | | | | | | | | | | | | Add the values of rcu_scheduler_active() and debug_locks() to the lockdep_rcu_dereference() output to help diagnose RCU lockdep splats that occur shortly after the scheduler starts. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1267631219-8713-4-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* rcu, cgroup: Relax the check in task_subsys_state() as early boot is now ↵Paul E. McKenney2010-03-04
| | | | | | | | | | | | | | | | | | | | | handled by lockdep-RCU This patch removes the check for !rcu_scheduler_active because this check has been incorporated into rcu_dereference_check(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1267631219-8713-3-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* rcu: Use wrapper function instead of exporting tasklist_lockPaul E. McKenney2010-03-04
| | | | | | | | | | | | | | | | | | | | | | Lockdep-RCU commit d11c563d exported tasklist_lock, which is not a good thing. This patch instead exports a function that uses lockdep to check whether tasklist_lock is held. Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com Cc: Christoph Hellwig <hch@lst.de> LKML-Reference: <1267631219-8713-1-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
*-. Merge branches 'core/futexes' and 'core/iommu' into core/urgentIngo Molnar2010-03-04
|\ \ | | | | | | | | | | | | | | | Merge reason: Switch from topical split to the stabilization track Signed-off-by: Ingo Molnar <mingo@elte.hu>
| | * x86/gart: Unexport gart_iommu_apertureFUJITA Tomonori2010-02-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I wrongly exported gart_iommu_aperture in the commit 42590a75019a50012f25a962246498dead428433. It's not necessary so let's unexport it. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Joerg Roedel <joerg.roedel@amd.com> LKML-Reference: <20100215113241P.fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | futex: Protect pid lookup in compat code with RCUThomas Gleixner2009-12-09
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | find_task_by_vpid() in compat_sys_get_robust_list() does not require tasklist_lock. It can be protected with rcu_read_lock as done in sys_get_robust_list() already. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Darren Hart <dvhltc@us.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org>
* | | sched, rcu: Fix rcu_dereference() for RCU-lockdepPaul E. McKenney2010-03-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make rcu_dereference() of runqueue data structures be rcu_dereference_sched(). Located-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <20100228163218.GD6846@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | Merge branch 'linus' into core/rcuIngo Molnar2010-03-01
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | Merge reason: Backmerge latest upstream to queue up dependent fix in the scheduler. Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * \ \ Merge branch 'x86-uv-for-linus' of ↵Linus Torvalds2010-02-28
| |\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-uv-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, uv: Remove recursion in uv_heartbeat_enable() x86, uv: uv_global_gru_mmr_address() macro fix x86, uv: Add serial number parameter to uv_bios_get_sn_info()
| | * | | x86, uv: Remove recursion in uv_heartbeat_enable()Roel Kluin2010-01-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The recursion is not needed and does not improve readability. Signed-off-by: Roel Kluin <roel.kluin@gmail.com> LKML-Reference: <4B45F13E.3040202@gmail.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | x86, uv: uv_global_gru_mmr_address() macro fixJack Steiner2010-01-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix bug in uv_global_gru_mmr_address macro. Macro failed to cast an int value to a long prior to a left shift > 32. Signed-off-by: Jack Steiner <steiner@sgi.com> LKML-Reference: <20100107161240.GA2610@sgi.com> Cc: <stable@kernel.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | x86, uv: Add serial number parameter to uv_bios_get_sn_info()Russ Anderson2009-12-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add system_serial_number to the information returned by uv_bios_get_sn_info() UV BIOS call. Signed-off-by: Russ Anderson <rja@sgi.com> LKML-Reference: <20091217165323.GA30774@sgi.com> Cc: Jack Steiner <steiner@sgi.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| * | | | Merge branch 'x86-ptrace-for-linus' of ↵Linus Torvalds2010-02-28
| |\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-ptrace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, ptrace: Remove set_stopped_child_used_math() in [x]fpregs_set x86, ptrace: Simplify xstateregs_get() ptrace: Fix ptrace_regset() comments and diagnose errors specifically parisc: Disable CONFIG_HAVE_ARCH_TRACEHOOK ptrace: Add support for generic PTRACE_GETREGSET/PTRACE_SETREGSET x86, ptrace: regset extensions to support xstate
| | * | | | x86, ptrace: Remove set_stopped_child_used_math() in [x]fpregs_setSuresh Siddha2010-02-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | init_fpu() already ensures that the used_math() is set for the stopped child. Remove the redundant set_stopped_child_used_math() in [x]fpregs_set() Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <20100222225240.642169080@sbs-t61.sc.intel.com> Acked-by: Rolan McGrath <roland@redhat.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | x86, ptrace: Simplify xstateregs_get()Suresh Siddha2010-02-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 48 bytes (bytes 464..511) of the xstateregs payload come from the kernel defined structure (xstate_fx_sw_bytes). Rest comes from the xstate regs structure in the thread struct. Instead of having multiple user_regset_copyout()'s, simplify the xstateregs_get() by first copying the SW bytes into the xstate regs structure in the thread structure and then using one user_regset_copyout() to copyout the xstateregs. Requested-by: Roland McGrath <roland@redhat.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <20100222225240.494688491@sbs-t61.sc.intel.com> Acked-by: Roland McGrath <roland@redhat.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Oleg Nesterov <oleg@redhat.com>
| | * | | | ptrace: Fix ptrace_regset() comments and diagnose errors specificallySuresh Siddha2010-02-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Return -EINVAL for the bad size and for unrecognized NT_* type in ptrace_regset() instead of -EIO. Also update the comments for this ptrace interface with more clarifications. Requested-by: Roland McGrath <roland@redhat.com> Requested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <20100222225240.397523600@sbs-t61.sc.intel.com> Acked-by: Roland McGrath <roland@redhat.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | parisc: Disable CONFIG_HAVE_ARCH_TRACEHOOKRoland McGrath2010-02-23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | > FYI, this commit broke tip:master on PARISC (other architectures are fine): > > kernel/built-in.o: In function `ptrace_request': > (.text.ptrace_request+0x2cc): undefined reference to `task_user_regset_view' This means that parisc failed to meet the documented requirements for setting CONFIG_HAVE_ARCH_TRACEHOOK, but set it anyway. If arch folks don't follow the specs, it defeats the whole purpose of having clear statements of requirements for arch code. Until parisc finishes up its requirements, disable CONFIG_HAVE_ARCH_TRACEHOOK. Signed-off-by: H. Peter Anvin <hpa@zytor.com> LKML-Reference: <20100222183707.8749D64C@magilla.sf.frob.com> Cc: <linux-parisc@vger.kernel.org> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Helge Deller <deller@gmx.de> Cc: James E.J. Bottomley <jejb@parisc-linux.org>
| | * | | | ptrace: Add support for generic PTRACE_GETREGSET/PTRACE_SETREGSETSuresh Siddha2010-02-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Generic support for PTRACE_GETREGSET/PTRACE_SETREGSET commands which export the regsets supported by each architecture using the correponding NT_* types. These NT_* types are already part of the userland ABI, used in representing the architecture specific register sets as different NOTES in an ELF core file. 'addr' parameter for the ptrace system call encode the REGSET type (using the corresppnding NT_* type) and the 'data' parameter points to the struct iovec having the user buffer and the length of that buffer. struct iovec iov = { buf, len}; ret = ptrace(PTRACE_GETREGSET/PTRACE_SETREGSET, pid, NT_XXX_TYPE, &iov); On successful completion, iov.len will be updated by the kernel specifying how much the kernel has written/read to/from the user's iov.buf. x86 extended state registers are primarily exported using this interface. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <20100211195614.886724710@sbs-t61.sc.intel.com> Acked-by: Hongjiu Lu <hjl.tools@gmail.com> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | x86, ptrace: regset extensions to support xstateSuresh Siddha2010-02-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add the xstate regset support which helps extend the kernel ptrace and the core-dump interfaces to support AVX state etc. This regset interface is designed to support all the future state that gets supported using xsave/xrstor infrastructure. Looking at the memory layout saved by "xsave", one can't say which state is represented in the memory layout. This is because if a particular state is in init state, in the xsave hdr it can be represented by bit '0'. And hence we can't really say by the xsave header wether a state is in init state or the state is not saved in the memory layout. And hence the xsave memory layout available through this regset interface uses SW usable bytes [464..511] to convey what state is represented in the memory layout. First 8 bytes of the sw_usable_bytes[464..467] will be set to OS enabled xstate mask(which is same as the 64bit mask returned by the xgetbv's xCR0). The note NT_X86_XSTATE represents the extended state information in the core file, using the above mentioned memory layout. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> LKML-Reference: <20100211195614.802495327@sbs-t61.sc.intel.com> Signed-off-by: Hongjiu Lu <hjl.tools@gmail.com> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| * | | | | Merge branch 'x86-pci-for-linus' of ↵Linus Torvalds2010-02-28
| |\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-pci-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86: Enable NMI on all cpus on UV vgaarb: Add user selectability of the number of GPUS in a system vgaarb: Fix VGA arbiter to accept PCI domains other than 0 x86, uv: Update UV arch to target Legacy VGA I/O correctly. pci: Update pci_set_vga_state() to call arch functions
| | * | | | | x86: Enable NMI on all cpus on UVRuss Anderson2010-02-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Enable NMI on all cpus in UV system and add an NMI handler to dump_stack on each cpu. By default on x86 all the cpus except the boot cpu have NMI masked off. This patch enables NMI on all cpus in UV system and adds an NMI handler to dump_stack on each cpu. This way if a system hangs we can NMI the machine and get a backtrace from all the cpus. Version 2: Use x86_platform driver mechanism for nmi init, per Ingo's suggestion. Version 3: Clean up Ingo's nits. Signed-off-by: Russ Anderson <rja@sgi.com> LKML-Reference: <20100226164912.GA24439@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
| | * | | | | vgaarb: Add user selectability of the number of GPUS in a systemMike Travis2010-02-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Update the VGA Arbiter to allow the user to select the number of GPU's supported in a system. v2: simplify setting of MAX_USER_CARDS, revert back to original default of 16 Signed-off-by: Mike Travis <travis@sgi.com> LKML-Reference: <4B68D51D.6090401@sgi.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Robin Holt <holt@sgi.com> Cc: Jack Steiner <steiner@sgi.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jesse Barnes <jbarnes@virtuousgeek.org> Cc: David Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | | vgaarb: Fix VGA arbiter to accept PCI domains other than 0Mike Travis2010-02-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Update the VGA Arbiter to accept PCI Domains other than 0. Signed-off-by: Mike Travis <travis@sgi.com> LKML-Reference: <201002022238.o12McFe8018730@imap1.linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Robin Holt <holt@sgi.com> Cc: Jack Steiner <steiner@sgi.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jesse Barnes <jbarnes@virtuousgeek.org> Cc: David Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | | x86, uv: Update UV arch to target Legacy VGA I/O correctly.Mike Travis2010-02-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add function to direct Legacy VGA I/O traffic to correct I/O Hub. Signed-off-by: Mike Travis <travis@sgi.com> LKML-Reference: <201002022238.o12McEbi018727@imap1.linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Robin Holt <holt@sgi.com> Cc: Jack Steiner <steiner@sgi.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jesse Barnes <jbarnes@virtuousgeek.org> Cc: David Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | | pci: Update pci_set_vga_state() to call arch functionsMike Travis2010-02-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Update pci_set_vga_state to call arch dependent functions to enable Legacy VGA I/O transactions to be redirected to correct target. [akpm@linux-foundation.org: make pci_register_set_vga_state() __init] Signed-off-by: Mike Travis <travis@sgi.com> LKML-Reference: <201002022238.o12McE1J018723@imap1.linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Robin Holt <holt@sgi.com> Cc: Jack Steiner <steiner@sgi.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Jesse Barnes <jbarnes@virtuousgeek.org> Cc: David Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| * | | | | | Merge branch 'x86-setup-for-linus' of ↵Linus Torvalds2010-02-28
| |\ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-setup-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, setup: Don't skip mode setting for the standard VGA modes x86-64, setup: Inhibit decompressor output if video info is invalid x86, setup: When restoring the screen, update boot_params.screen_info
| | * | | | | | x86, setup: Don't skip mode setting for the standard VGA modesH. Peter Anvin2010-02-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The code for setting standard VGA modes probes for the current mode, and skips the mode setting if the mode is 3 (color text 80x25) or 7 (mono text 80x25). Unfortunately, there are BIOSes, including the VMware BIOS, which report the previous mode if function 0F is queried while the screen is in a VESA mode, and of course, nothing can help a mode poked directly into the hardware. As such, the safe option is to set the mode anyway, and only query to see if we should be using mode 7 rather than mode 3. People who don't want any mode setting at all should probably use vga=0x0f04 (VIDEO_CURRENT_MODE). It's possible that should be the kernel default. Reported-by Rene Arends <R.R.Arends@hro.nl> Signed-off-by: H. Peter Anvin <hpa@zytor.com> LKML-Reference: <tip-*@git.kernel.org>
| | * | | | | | x86-64, setup: Inhibit decompressor output if video info is invalidH. Peter Anvin2010-02-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Inhibit output from the kernel decompressor if the video information is invalid. This was already the case for 32 bits, make 64 bits match. Signed-off-by: H. Peter Anvin <hpa@zytor.com> LKML-Reference: <tip-*@git.kernel.org>
| | * | | | | | x86, setup: When restoring the screen, update boot_params.screen_infoH. Peter Anvin2010-02-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When we restore the screen content after a mode change, we return the cursor to its former position. However, we need to also update boot_params.screen_info accordingly, so that the decompression code knows where on the screen the cursor is. Just in case the video BIOS does something extra screwy, read the cursor position back from the BIOS instead of relying on it doing the right thing. While we're at it, make sure we cap the cursor position to the new screen coordinates. Reported-by: Wim Osterholt <wim@djo.tudelft.nl> Bugzilla-Reference: http://bugzilla.kernel.org/show_bug.cgi?id=15329 Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| * | | | | | | Merge branch 'x86-rwsem-for-linus' of ↵Linus Torvalds2010-02-28
| |\ \ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-rwsem-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86-64, rwsem: Avoid store forwarding hazard in __downgrade_write x86-64, rwsem: 64-bit xadd rwsem implementation x86: Fix breakage of UML from the changes in the rwsem system x86-64: support native xadd rwsem implementation x86: clean up rwsem type system
| | * | | | | | | x86-64, rwsem: Avoid store forwarding hazard in __downgrade_writeAvi Kivity2010-02-13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The Intel Architecture Optimization Reference Manual states that a short load that follows a long store to the same object will suffer a store forwading penalty, particularly if the two accesses use different addresses. Trivially, a long load that follows a short store will also suffer a penalty. __downgrade_write() in rwsem incurs both penalties: the increment operation will not be able to reuse a recently-loaded rwsem value, and its result will not be reused by any recently-following rwsem operation. A comment in the code states that this is because 64-bit immediates are special and expensive; but while they are slightly special (only a single instruction allows them), they aren't expensive: a test shows that two loops, one loading a 32-bit immediate and one loading a 64-bit immediate, both take 1.5 cycles per iteration. Fix this by changing __downgrade_write to use the same add instruction on i386 and on x86_64, so that it uses the same operand size as all the other rwsem functions. Signed-off-by: Avi Kivity <avi@redhat.com> LKML-Reference: <1266049992-17419-1-git-send-email-avi@redhat.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | | | | x86-64, rwsem: 64-bit xadd rwsem implementationH. Peter Anvin2010-01-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For x86-64, 32767 threads really is not enough. Change rwsem_count_t to a signed long, so that it is 64 bits on x86-64. This required the following changes to the assembly code: a) %z0 doesn't work on all versions of gcc! At least gcc 4.4.2 as shipped with Fedora 12 emits "ll" not "q" for 64 bits, even for integer operands. Newer gccs apparently do this correctly, but avoid this problem by using the _ASM_ macros instead of %z. b) 64 bits immediates are only allowed in "movq $imm,%reg" constructs... no others. Change some of the constraints to "e", and fix the one case where we would have had to use an invalid immediate -- in that case, we only care about the upper half anyway, so just access the upper half. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <tip-bafaecd11df15ad5b1e598adc7736afcd38ee13d@git.kernel.org>
| | * | | | | | | x86: Fix breakage of UML from the changes in the rwsem systemLinus Torvalds2010-01-18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The patches 5d0b7235d83eefdafda300656e97d368afcafc9a and bafaecd11df15ad5b1e598adc7736afcd38ee13d broke the UML build: On Sun, 17 Jan 2010, Ingo Molnar wrote: > > FYI, -tip testing found that these changes break the UML build: > > kernel/built-in.o: In function `__up_read': > /home/mingo/tip/arch/x86/include/asm/rwsem.h:192: undefined reference to `call_rwsem_wake' > kernel/built-in.o: In function `__up_write': > /home/mingo/tip/arch/x86/include/asm/rwsem.h:210: undefined reference to `call_rwsem_wake' > kernel/built-in.o: In function `__downgrade_write': > /home/mingo/tip/arch/x86/include/asm/rwsem.h:228: undefined reference to `call_rwsem_downgrade_wake' > kernel/built-in.o: In function `__down_read': > /home/mingo/tip/arch/x86/include/asm/rwsem.h:112: undefined reference to `call_rwsem_down_read_failed' > kernel/built-in.o: In function `__down_write_nested': > /home/mingo/tip/arch/x86/include/asm/rwsem.h:154: undefined reference to `call_rwsem_down_write_failed' > collect2: ld returned 1 exit status Add lib/rwsem_64.o to the UML subarch objects to fix. LKML-Reference: <alpine.LFD.2.00.1001171023440.13231@localhost.localdomain> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | | | | x86-64: support native xadd rwsem implementationLinus Torvalds2010-01-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This one is much faster than the spinlock based fallback rwsem code, with certain artifical benchmarks having shown 300%+ improvement on threaded page faults etc. Again, note the 32767-thread limit here. So this really does need that whole "make rwsem_count_t be 64-bit and fix the BIAS values to match" extension on top of it, but that is conceptually a totally independent issue. NOT TESTED! The original patch that this all was based on were tested by KAMEZAWA Hiroyuki, but maybe I screwed up something when I created the cleaned-up series, so caveat emptor.. Also note that it _may_ be a good idea to mark some more registers clobbered on x86-64 in the inline asms instead of saving/restoring them. They are inline functions, but they are only used in places where there are not a lot of live registers _anyway_, so doing for example the clobbers of %r8-%r11 in the asm wouldn't make the fast-path code any worse, and would make the slow-path code smaller. (Not that the slow-path really matters to that degree. Saving a few unnecessary registers is the _least_ of our problems when we hit the slow path. The instruction/cycle counting really only matters in the fast path). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <alpine.LFD.2.00.1001121810410.17145@localhost.localdomain> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | | | | x86: clean up rwsem type systemLinus Torvalds2010-01-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The fast version of the rwsems (the code that uses xadd) has traditionally only worked on x86-32, and as a result it mixes different kinds of types wildly - they just all happen to be 32-bit. We have "long", we have "__s32", and we have "int". To make it work on x86-64, the types suddenly matter a lot more. It can be either a 32-bit or 64-bit signed type, and both work (with the caveat that a 32-bit counter will only have 15 bits of effective write counters, so it's limited to 32767 users). But whatever type you choose, it needs to be used consistently. This makes a new 'rwsem_counter_t', that is a 32-bit signed type. For a 64-bit type, you'd need to also update the BIAS values. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <alpine.LFD.2.00.1001121755220.17145@localhost.localdomain> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| * | | | | | | | Merge branch 'x86-numa-for-linus' of ↵Linus Torvalds2010-02-28
| |\ \ \ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-numa-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86, numa: Remove configurable node size support for numa emulation x86, numa: Add fixed node size option for numa emulation x86, numa: Fix numa emulation calculation of big nodes x86, acpi: Map hotadded cpu to correct node.
| | * | | | | | | | x86, numa: Remove configurable node size support for numa emulationDavid Rientjes2010-02-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that numa=fake=<size>[MG] is implemented, it is possible to remove configurable node size support. The command-line parsing was already broken (numa=fake=*128, for example, would not work) and since fake nodes are now interleaved over physical nodes, this support is no longer required. Signed-off-by: David Rientjes <rientjes@google.com> LKML-Reference: <alpine.DEB.2.00.1002151343080.26927@chino.kir.corp.google.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | | | | | x86, numa: Add fixed node size option for numa emulationDavid Rientjes2010-02-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | numa=fake=N specifies the number of fake nodes, N, to partition the system into and then allocates them by interleaving over physical nodes. This requires knowledge of the system capacity when attempting to allocate nodes of a certain size: either very large nodes to benchmark scalability of code that operates on individual nodes, or very small nodes to find bugs in the VM. This patch introduces numa=fake=<size>[MG] so it is possible to specify the size of each node to allocate. When used, nodes of the size specified will be allocated and interleaved over the set of physical nodes. FAKE_NODE_MIN_SIZE was also moved to the more-appropriate include/asm/numa_64.h. Signed-off-by: David Rientjes <rientjes@google.com> LKML-Reference: <alpine.DEB.2.00.1002151342510.26927@chino.kir.corp.google.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | | | | | x86, numa: Fix numa emulation calculation of big nodesDavid Rientjes2010-02-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | numa=fake=N uses split_nodes_interleave() to partition the system into N fake nodes. Each node size must have be a multiple of FAKE_NODE_MIN_SIZE, otherwise it is possible to get strange alignments. Because of this, the remaining memory from each node when rounded to FAKE_NODE_MIN_SIZE is consolidated into a number of "big nodes" that are bigger than the rest. The calculation of the number of big nodes is incorrect since it is using a logical AND operator when it should be multiplying the rounded-off portion of each node with N. Signed-off-by: David Rientjes <rientjes@google.com> LKML-Reference: <alpine.DEB.2.00.1002151342230.26927@chino.kir.corp.google.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | | | | | x86, acpi: Map hotadded cpu to correct node.Haicheng Li2010-02-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When hotadd new cpu to system, if its affinitive node is online, should map the cpu to its own node. Otherwise, let kernel select one online node for the new cpu later. Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com> LKML-Reference: <4B6AAA39.6000300@linux.intel.com> Tested-by: Thomas Renninger <trenn@suse.de> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| * | | | | | | | | Merge branch 'x86-mtrr-for-linus' of ↵Linus Torvalds2010-02-28
| |\ \ \ \ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'x86-mtrr-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: x86: Convert set_atomicity_lock to raw_spinlock x86, mtrr: Kill over the top warn x86, mtrr: Constify struct mtrr_ops
| | * | | | | | | | | x86: Convert set_atomicity_lock to raw_spinlockThomas Gleixner2010-02-16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| | * | | | | | | | | x86, mtrr: Kill over the top warnAlan Cox2010-02-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fixes bugzilla: http://bugzilla.kernel.org/show_bug.cgi?id=12558 Fixes bugzilla: http://bugzilla.kernel.org/show_bug.cgi?id=12317 (and if this really needed to be a warn you'd be responding to the bugs left in bugzilla from it...) Signed-off-by: Alan Cox <alan@linux.intel.com> LKML-Reference: <20100208100239.2568.2940.stgit@localhost.localdomain> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
| | * | | | | | | | | x86, mtrr: Constify struct mtrr_opsEmese Revfy2010-02-01
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is part of the ops structure constification effort started by Arjan van de Ven et al. Benefits of this constification: * prevents modification of data that is shared (referenced) by many other structure instances at runtime * detects/prevents accidental (but not intentional) modification attempts on archs that enforce read-only kernel data at runtime * potentially better optimized code as the compiler can assume that the const data cannot be changed * the compiler/linker move const data into .rodata and therefore exclude them from false sharing Signed-off-by: Emese Revfy <re.emese@gmail.com> LKML-Reference: <4B65D712.3080804@gmail.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-14 00:07:31 -0500