From 9414e99672271adcc661f3c160a30b374179b92f Mon Sep 17 00:00:00 2001 From: Phil Carmody Date: Wed, 28 Apr 2010 12:09:16 -0500 Subject: [PATCH] oprofile: protect from not being in an IRQ context http://lkml.org/lkml/2010/4/27/285 Protect against dereferencing regs when it's NULL, and force a magic number into pc to prevent too deep processing. This approach permits the dropped samples to be tallied as invalid Instruction Pointer events. e.g. output from about 15mins at 10kHz sample rate: Nr. samples received: 2565380 Nr. samples lost invalid pc: 4 Signed-off-by: Phil Carmody Signed-off-by: Robert Richter --- drivers/oprofile/cpu_buffer.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c index 0ac8b06..219f79e 100644 --- a/drivers/oprofile/cpu_buffer.c +++ b/drivers/oprofile/cpu_buffer.c @@ -319,8 +319,16 @@ void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs, void oprofile_add_sample(struct pt_regs * const regs, unsigned long event) { - int is_kernel = !user_mode(regs); - unsigned long pc = profile_pc(regs); + int is_kernel; + unsigned long pc; + + if (likely(regs)) { + is_kernel = !user_mode(regs); + pc = profile_pc(regs); + } else { + is_kernel = 0; /* This value will not be used */ + pc = ESCAPE_CODE; /* as this causes an early return. */ + } __oprofile_add_ext_sample(pc, regs, event, is_kernel); } -- 2.7.4