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authorSteven Rostedt <srostedt@redhat.com>2008-11-10 21:46:00 -0500
committerSteven Rostedt <srostedt@redhat.com>2008-11-10 21:47:35 -0500
commitbf5e6519b85b3853f2d0bb4f17a4e2eaeffeb574 (patch)
treed5560a28100aed24e3bb09e68c17a0ea1fbde07b /kernel
parent3ad4f597058301c97f362e500a32f63f5c950a45 (diff)
downloadlinux-bf5e6519b85b3853f2d0bb4f17a4e2eaeffeb574.tar.bz2
ftrace: disable tracing on resize
Impact: fix for bug on resize This patch addresses the bug found here: http://bugzilla.kernel.org/show_bug.cgi?id=11996 When ftrace converted to the new unified trace buffer, the resizing of the buffer was not protected as much as it was originally. If tracing is performed while the resize occurs, then the buffer can be corrupted. This patch disables all ftrace buffer modifications before a resize takes place. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9f3b478f9171..abfa8103d046 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2676,7 +2676,7 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
{
unsigned long val;
char buf[64];
- int ret;
+ int ret, cpu;
struct trace_array *tr = filp->private_data;
if (cnt >= sizeof(buf))
@@ -2704,6 +2704,14 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
goto out;
}
+ /* disable all cpu buffers */
+ for_each_tracing_cpu(cpu) {
+ if (global_trace.data[cpu])
+ atomic_inc(&global_trace.data[cpu]->disabled);
+ if (max_tr.data[cpu])
+ atomic_inc(&max_tr.data[cpu]->disabled);
+ }
+
if (val != global_trace.entries) {
ret = ring_buffer_resize(global_trace.buffer, val);
if (ret < 0) {
@@ -2735,6 +2743,13 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
if (tracing_disabled)
cnt = -ENOMEM;
out:
+ for_each_tracing_cpu(cpu) {
+ if (global_trace.data[cpu])
+ atomic_dec(&global_trace.data[cpu]->disabled);
+ if (max_tr.data[cpu])
+ atomic_dec(&max_tr.data[cpu]->disabled);
+ }
+
max_tr.entries = global_trace.entries;
mutex_unlock(&trace_types_lock);