diff options
| author | J. Bruce Fields <bfields@redhat.com> | 2010-12-17 13:29:07 -0500 |
|---|---|---|
| committer | J. Bruce Fields <bfields@redhat.com> | 2010-12-17 13:29:07 -0500 |
| commit | ec66ee3797e5848356cf593c6ec7aabf30a00cf1 (patch) | |
| tree | 7ed5c84cc914644ffa1cd1b6a2b45db53fc224e8 /kernel/trace/trace.c | |
| parent | 1205065764f2eda3216ebe213143f69891ee3460 (diff) | |
| parent | b0c3844d8af6b9f3f18f31e1b0502fbefa2166be (diff) | |
Merge commit 'v2.6.37-rc6' into for-2.6.38
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 82d9b8106cd0..c380612273bf 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -17,7 +17,6 @@ #include <linux/writeback.h> #include <linux/kallsyms.h> #include <linux/seq_file.h> -#include <linux/smp_lock.h> #include <linux/notifier.h> #include <linux/irqflags.h> #include <linux/debugfs.h> @@ -1284,6 +1283,8 @@ void trace_dump_stack(void) __ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count()); } +static DEFINE_PER_CPU(int, user_stack_count); + void ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc) { @@ -1302,6 +1303,18 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc) if (unlikely(in_nmi())) return; + /* + * prevent recursion, since the user stack tracing may + * trigger other kernel events. + */ + preempt_disable(); + if (__this_cpu_read(user_stack_count)) + goto out; + + __this_cpu_inc(user_stack_count); + + + event = trace_buffer_lock_reserve(buffer, TRACE_USER_STACK, sizeof(*entry), flags, pc); if (!event) @@ -1319,6 +1332,11 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc) save_stack_trace_user(&trace); if (!filter_check_discard(call, entry, buffer, event)) ring_buffer_unlock_commit(buffer, event); + + __this_cpu_dec(user_stack_count); + + out: + preempt_enable(); } #ifdef UNUSED |