diff options
author | Frederic Weisbecker <fweisbec@gmail.com> | 2009-04-01 16:53:08 -0400 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2009-04-07 08:02:03 -0400 |
commit | b0dfa978c7a1699fb3506fbfcba0b6a5c4bd17ae (patch) | |
tree | 4e52215e4d2f67c7063f813b9d788763d6f341a8 | |
parent | 5ab8026a3016fbed5c73aa070d9f6989cf791099 (diff) |
tracing/ftrace: alloc the started cpumask for the trace file
Impact: fix a crash while cat trace file
Currently we are using a cpumask to remind each cpu where a
trace occured. It lets us notice the user that a cpu just had
its first trace.
But on latest -tip we have the following crash once we cat the trace
file:
IP: [<c0270c4a>] print_trace_fmt+0x45/0xe7
*pde = 00000000
Oops: 0000 [#1] PREEMPT SMP
last sysfs file: /sys/class/net/eth0/carrier
Pid: 3897, comm: cat Not tainted (2.6.29-tip-02825-g0f22972-dirty #81)
EIP: 0060:[<c0270c4a>] EFLAGS: 00010297 CPU: 0
EIP is at print_trace_fmt+0x45/0xe7
EAX: 00000000 EBX: 00000000 ECX: c12d9e98 EDX: ccdb7010
ESI: d31f4000 EDI: 00322401 EBP: d31f3f10 ESP: d31f3efc
DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
Process cat (pid: 3897, ti=d31f2000 task=d3b3cf20 task.ti=d31f2000)
Stack:
d31f4080 ccdb7010 d31f4000 d691fe70 ccdb7010 d31f3f24 c0270e5c d31f4000
d691fe70 d31f4000 d31f3f34 c02718e8 c12d9e98 d691fe70 d31f3f70 c02bfc33
00001000 09130000 d3b46e00 d691fe98 00000000 00000079 00000001 00000000
Call Trace:
[<c0270e5c>] ? print_trace_line+0x170/0x17c
[<c02718e8>] ? s_show+0xa7/0xbd
[<c02bfc33>] ? seq_read+0x24a/0x327
[<c02bf9e9>] ? seq_read+0x0/0x327
[<c02ab18b>] ? vfs_read+0x86/0xe1
[<c02ab289>] ? sys_read+0x40/0x65
[<c0202d8f>] ? sysenter_do_call+0x12/0x3c
Code: 00 00 00 89 45 ec f7 c7 00 20 00 00 89 55 f0 74 4e f6 86 98 10 00 00 02 74 45 8b 86 8c 10 00 00 8b 9e a8 10 00 00 e8 52 f3 ff ff <0f> a3 03 19 c0 85 c0 75 2b 8b 86 8c 10 00 00 8b 9e a8 10 00 00
EIP: [<c0270c4a>] print_trace_fmt+0x45/0xe7 SS:ESP 0068:d31f3efc
CR2: 0000000000000000
---[ end trace aa9cf38e5ebed9dd ]---
This is because we alloc the iter->started cpumask on tracing_pipe_open but
not on tracing_open.
It hadn't been noticed until now because we need to have ring buffer overruns
to activate the starting of cpu buffer detection.
Also, we need a check to not print the messagge for the first trace on the file.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1238619188-6109-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r-- | kernel/trace/trace.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 2230b46f9e1c..fc8c7d66832b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c | |||
@@ -1632,7 +1632,11 @@ static void test_cpu_buff_start(struct trace_iterator *iter) | |||
1632 | return; | 1632 | return; |
1633 | 1633 | ||
1634 | cpumask_set_cpu(iter->cpu, iter->started); | 1634 | cpumask_set_cpu(iter->cpu, iter->started); |
1635 | trace_seq_printf(s, "##### CPU %u buffer started ####\n", iter->cpu); | 1635 | |
1636 | /* Don't print started cpu buffer for the first entry of the trace */ | ||
1637 | if (iter->idx > 1) | ||
1638 | trace_seq_printf(s, "##### CPU %u buffer started ####\n", | ||
1639 | iter->cpu); | ||
1636 | } | 1640 | } |
1637 | 1641 | ||
1638 | static enum print_line_t print_trace_fmt(struct trace_iterator *iter) | 1642 | static enum print_line_t print_trace_fmt(struct trace_iterator *iter) |
@@ -1867,6 +1871,11 @@ __tracing_open(struct inode *inode, struct file *file) | |||
1867 | if (current_trace) | 1871 | if (current_trace) |
1868 | *iter->trace = *current_trace; | 1872 | *iter->trace = *current_trace; |
1869 | 1873 | ||
1874 | if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) | ||
1875 | goto fail; | ||
1876 | |||
1877 | cpumask_clear(iter->started); | ||
1878 | |||
1870 | if (current_trace && current_trace->print_max) | 1879 | if (current_trace && current_trace->print_max) |
1871 | iter->tr = &max_tr; | 1880 | iter->tr = &max_tr; |
1872 | else | 1881 | else |
@@ -1917,6 +1926,7 @@ __tracing_open(struct inode *inode, struct file *file) | |||
1917 | if (iter->buffer_iter[cpu]) | 1926 | if (iter->buffer_iter[cpu]) |
1918 | ring_buffer_read_finish(iter->buffer_iter[cpu]); | 1927 | ring_buffer_read_finish(iter->buffer_iter[cpu]); |
1919 | } | 1928 | } |
1929 | free_cpumask_var(iter->started); | ||
1920 | fail: | 1930 | fail: |
1921 | mutex_unlock(&trace_types_lock); | 1931 | mutex_unlock(&trace_types_lock); |
1922 | kfree(iter->trace); | 1932 | kfree(iter->trace); |
@@ -1960,6 +1970,7 @@ static int tracing_release(struct inode *inode, struct file *file) | |||
1960 | 1970 | ||
1961 | seq_release(inode, file); | 1971 | seq_release(inode, file); |
1962 | mutex_destroy(&iter->mutex); | 1972 | mutex_destroy(&iter->mutex); |
1973 | free_cpumask_var(iter->started); | ||
1963 | kfree(iter->trace); | 1974 | kfree(iter->trace); |
1964 | kfree(iter); | 1975 | kfree(iter); |
1965 | return 0; | 1976 | return 0; |