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authorNick Piggin <nickpiggin@yahoo.com.au>2005-11-09 00:39:01 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2005-11-09 10:56:33 -0500
commit5bfb5d690f36d316a5f3b4f7775fda996faa6b12 (patch)
treeea53f15293d1ddb49c316eb65df85e939a4f6e5e /arch/i386
parentede3d0fba99520f268067917b50858d788bc41da (diff)
[PATCH] sched: disable preempt in idle tasks
Run idle threads with preempt disabled. Also corrected a bugs in arm26's cpu_idle (make it actually call schedule()). How did it ever work before? Might fix the CPU hotplugging hang which Nigel Cunningham noted. We think the bug hits if the idle thread is preempted after checking need_resched() and before going to sleep, then the CPU offlined. After calling stop_machine_run, the CPU eventually returns from preemption and into the idle thread and goes to sleep. The CPU will continue executing previous idle and have no chance to call play_dead. By disabling preemption until we are ready to explicitly schedule, this bug is fixed and the idle threads generally become more robust. From: alexs <ashepard@u.washington.edu> PPC build fix From: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> MIPS build fix Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/i386')
-rw-r--r--arch/i386/kernel/process.c4
-rw-r--r--arch/i386/kernel/smpboot.c1
2 files changed, 4 insertions, 1 deletions
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index 7a14fdfd3af9..5296e284ea36 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -179,7 +179,7 @@ static inline void play_dead(void)
179 */ 179 */
180void cpu_idle(void) 180void cpu_idle(void)
181{ 181{
182 int cpu = raw_smp_processor_id(); 182 int cpu = smp_processor_id();
183 183
184 /* endless idle loop with no priority at all */ 184 /* endless idle loop with no priority at all */
185 while (1) { 185 while (1) {
@@ -201,7 +201,9 @@ void cpu_idle(void)
201 __get_cpu_var(irq_stat).idle_timestamp = jiffies; 201 __get_cpu_var(irq_stat).idle_timestamp = jiffies;
202 idle(); 202 idle();
203 } 203 }
204 preempt_enable_no_resched();
204 schedule(); 205 schedule();
206 preempt_disable();
205 } 207 }
206} 208}
207 209
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index 47ec76794d02..bc5a9d97466b 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -485,6 +485,7 @@ static void __devinit start_secondary(void *unused)
485 * things done here to the most necessary things. 485 * things done here to the most necessary things.
486 */ 486 */
487 cpu_init(); 487 cpu_init();
488 preempt_disable();
488 smp_callin(); 489 smp_callin();
489 while (!cpu_isset(smp_processor_id(), smp_commenced_mask)) 490 while (!cpu_isset(smp_processor_id(), smp_commenced_mask))
490 rep_nop(); 491 rep_nop();