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authorSteven Rostedt <srostedt@redhat.com>2011-06-07 09:26:46 -0400
committerSteven Rostedt <rostedt@goodmis.org>2011-06-07 14:49:19 -0400
commita4f18ed11a4ddf327dd91cd19e237278600ad327 (patch)
treebbe96241c6db2be16e881920a3312ec937ed7cd1 /kernel/trace/ftrace.c
parent265a5b7ee3eb21a4d0e53e17d59ba6eada91af39 (diff)
ftrace: Revert 8ab2b7efd ftrace: Remove unnecessary disabling of irqs
Revert the commit that removed the disabling of interrupts around the initial modifying of mcount callers to nops, and update the comment. The original comment was outdated and stated that the interrupts were being disabled to prevent kstop machine, which was required with the old ftrace daemon, but was no longer the case. What the comment failed to mention was that interrupts needed to be disabled to keep interrupts from preempting the modifying of the code and then executing the code that was partially modified. Revert the commit and update the comment. Reported-by: Richard W.M. Jones <rjones@redhat.com> Tested-by: Richard W.M. Jones <rjones@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/ftrace.c')
-rw-r--r--kernel/trace/ftrace.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 204b3eb4e690..908038f57440 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3330,6 +3330,7 @@ static int ftrace_process_locs(struct module *mod,
3330{ 3330{
3331 unsigned long *p; 3331 unsigned long *p;
3332 unsigned long addr; 3332 unsigned long addr;
3333 unsigned long flags;
3333 3334
3334 mutex_lock(&ftrace_lock); 3335 mutex_lock(&ftrace_lock);
3335 p = start; 3336 p = start;
@@ -3346,7 +3347,13 @@ static int ftrace_process_locs(struct module *mod,
3346 ftrace_record_ip(addr); 3347 ftrace_record_ip(addr);
3347 } 3348 }
3348 3349
3350 /*
3351 * Disable interrupts to prevent interrupts from executing
3352 * code that is being modified.
3353 */
3354 local_irq_save(flags);
3349 ftrace_update_code(mod); 3355 ftrace_update_code(mod);
3356 local_irq_restore(flags);
3350 mutex_unlock(&ftrace_lock); 3357 mutex_unlock(&ftrace_lock);
3351 3358
3352 return 0; 3359 return 0;