perf_events: Undo some recursion damage

Make perf_swevent_get_recursion_context return a context number
and disable preemption.

This could be used to remove the IRQ disable from the trace bit
and index the per-cpu buffer with.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091123103819.993226816@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 6 deletions

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 41b6dd963daa..9189cbe86079 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -481,8 +481,8 @@ static void prof_syscall_enter(struct pt_regs *regs, long id)
         unsigned long flags;
         char *trace_buf;
         char *raw_data;
-        int *recursion;
         int syscall_nr;
+        int rctx;
         int size;
         int cpu;
 
@@ -506,7 +506,8 @@ static void prof_syscall_enter(struct pt_regs *regs, long id)
         /* Protect the per cpu buffer, begin the rcu read side */
         local_irq_save(flags);
 
-        if (perf_swevent_get_recursion_context(&recursion))
+        rctx = perf_swevent_get_recursion_context();
+        if (rctx < 0)
                 goto end_recursion;
 
         cpu = smp_processor_id();
@@ -530,7 +531,7 @@ static void prof_syscall_enter(struct pt_regs *regs, long id)
         perf_tp_event(sys_data->enter_id, 0, 1, rec, size);
 
 end:
-        perf_swevent_put_recursion_context(recursion);
+        perf_swevent_put_recursion_context(rctx);
 end_recursion:
         local_irq_restore(flags);
 }
@@ -582,7 +583,7 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret)
         int syscall_nr;
         char *trace_buf;
         char *raw_data;
-        int *recursion;
+        int rctx;
         int size;
         int cpu;
 
@@ -609,7 +610,8 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret)
         /* Protect the per cpu buffer, begin the rcu read side */
         local_irq_save(flags);
 
-        if (perf_swevent_get_recursion_context(&recursion))
+        rctx = perf_swevent_get_recursion_context();
+        if (rctx < 0)
                 goto end_recursion;
 
         cpu = smp_processor_id();
@@ -634,7 +636,7 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret)
         perf_tp_event(sys_data->exit_id, 0, 1, rec, size);
 
 end:
-        perf_swevent_put_recursion_context(recursion);
+        perf_swevent_put_recursion_context(rctx);
 end_recursion:
         local_irq_restore(flags);
 }