From 211117ff09b7d81d91b7857651587128ed8b13d9 Mon Sep 17 00:00:00 2001 From: Robert Richter Date: Tue, 9 Dec 2008 02:13:25 +0100 Subject: [PATCH] oprofile: fix lost sample counter The number of lost samples could be greater than the number of received samples. This patches fixes this. The implementation introduces return values for add_sample() and add_code(). Signed-off-by: Robert Richter --- drivers/oprofile/cpu_buffer.c | 83 ++++++++++++++++++++++------------- 1 file changed, 53 insertions(+), 30 deletions(-) diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c index 7f7fc958297..61090969158 100644 --- a/drivers/oprofile/cpu_buffer.c +++ b/drivers/oprofile/cpu_buffer.c @@ -145,32 +145,31 @@ void end_cpu_work(void) flush_scheduled_work(); } -static inline void +static inline int add_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc, unsigned long event) { struct op_entry entry; + int ret; - if (cpu_buffer_write_entry(&entry)) - goto Error; + ret = cpu_buffer_write_entry(&entry); + if (ret) + return ret; entry.sample->eip = pc; entry.sample->event = event; - if (cpu_buffer_write_commit(&entry)) - goto Error; + ret = cpu_buffer_write_commit(&entry); + if (ret) + return ret; - return; - -Error: - cpu_buf->sample_lost_overflow++; - return; + return 0; } -static inline void +static inline int add_code(struct oprofile_cpu_buffer *buffer, unsigned long value) { - add_sample(buffer, ESCAPE_CODE, value); + return add_sample(buffer, ESCAPE_CODE, value); } /* This must be safe from any context. It's safe writing here @@ -201,17 +200,25 @@ static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc, /* notice a switch from user->kernel or vice versa */ if (cpu_buf->last_is_kernel != is_kernel) { cpu_buf->last_is_kernel = is_kernel; - add_code(cpu_buf, is_kernel); + if (add_code(cpu_buf, is_kernel)) + goto fail; } /* notice a task switch */ if (cpu_buf->last_task != task) { cpu_buf->last_task = task; - add_code(cpu_buf, (unsigned long)task); + if (add_code(cpu_buf, (unsigned long)task)) + goto fail; } - add_sample(cpu_buf, pc, event); + if (add_sample(cpu_buf, pc, event)) + goto fail; + return 1; + +fail: + cpu_buf->sample_lost_overflow++; + return 0; } static int oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf) @@ -266,37 +273,49 @@ void oprofile_add_ibs_sample(struct pt_regs * const regs, int is_kernel = !user_mode(regs); struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer); struct task_struct *task; + int fail = 0; cpu_buf->sample_received++; /* notice a switch from user->kernel or vice versa */ if (cpu_buf->last_is_kernel != is_kernel) { + if (add_code(cpu_buf, is_kernel)) + goto fail; cpu_buf->last_is_kernel = is_kernel; - add_code(cpu_buf, is_kernel); } /* notice a task switch */ if (!is_kernel) { task = current; if (cpu_buf->last_task != task) { + if (add_code(cpu_buf, (unsigned long)task)) + goto fail; cpu_buf->last_task = task; - add_code(cpu_buf, (unsigned long)task); } } - add_code(cpu_buf, ibs_code); - add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]); - add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]); - add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]); + fail = fail || add_code(cpu_buf, ibs_code); + fail = fail || add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]); + fail = fail || add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]); + fail = fail || add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]); if (ibs_code == IBS_OP_BEGIN) { - add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]); - add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]); - add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]); + fail = fail || add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]); + fail = fail || add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]); + fail = fail || add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]); } + if (fail) + goto fail; + if (backtrace_depth) oprofile_ops.backtrace(regs, backtrace_depth); + + return; + +fail: + cpu_buf->sample_lost_overflow++; + return; } #endif @@ -318,13 +337,17 @@ void oprofile_add_trace(unsigned long pc) * broken frame can give an eip with the same value as an * escape code, abort the trace if we get it */ - if (pc == ESCAPE_CODE) { - cpu_buf->tracing = 0; - cpu_buf->backtrace_aborted++; - return; - } + if (pc == ESCAPE_CODE) + goto fail; + + if (add_sample(cpu_buf, pc, 0)) + goto fail; - add_sample(cpu_buf, pc, 0); + return; +fail: + cpu_buf->tracing = 0; + cpu_buf->backtrace_aborted++; + return; } /* -- 2.41.1