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>

2 files changed, 16 insertions, 12 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 22e6f68b05b3..79ce6a2bd74f 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1213,7 +1213,7 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
 	unsigned long irq_flags;
 	char *trace_buf;
 	char *raw_data;
-	int *recursion;
+	int rctx;
 
 	pc = preempt_count();
 	__size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
@@ -1229,7 +1229,8 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
 	 */
 	local_irq_save(irq_flags);
 
-	if (perf_swevent_get_recursion_context(&recursion))
+	rctx = perf_swevent_get_recursion_context();
+	if (rctx < 0)
 		goto end_recursion;
 
 	__cpu = smp_processor_id();
@@ -1258,7 +1259,7 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
 	perf_tp_event(call->id, entry->ip, 1, entry, size);
 
 end:
-	perf_swevent_put_recursion_context(recursion);
+	perf_swevent_put_recursion_context(rctx);
 end_recursion:
 	local_irq_restore(irq_flags);
 
@@ -1276,8 +1277,8 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
 	int size, __size, i, pc, __cpu;
 	unsigned long irq_flags;
 	char *trace_buf;
-	int *recursion;
 	char *raw_data;
+	int rctx;
 
 	pc = preempt_count();
 	__size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
@@ -1293,7 +1294,8 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
 	 */
 	local_irq_save(irq_flags);
 
-	if (perf_swevent_get_recursion_context(&recursion))
+	rctx = perf_swevent_get_recursion_context();
+	if (rctx < 0)
 		goto end_recursion;
 
 	__cpu = smp_processor_id();
@@ -1323,7 +1325,7 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
 	perf_tp_event(call->id, entry->ret_ip, 1, entry, size);
 
 end:
-	perf_swevent_put_recursion_context(recursion);
+	perf_swevent_put_recursion_context(rctx);
 end_recursion:
 	local_irq_restore(irq_flags);
 
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);
 }