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authorJens Axboe <jens.axboe@oracle.com>2008-05-28 14:45:33 +0200
committerJens Axboe <jens.axboe@oracle.com>2008-05-28 14:49:27 +0200
commit64565911cdb57c2f512a9715b985b5617402cc67 (patch)
tree1c8a3d03fcb0e620c8f2244962fb249cff51fec4 /block
parent4722dc52a891ab6cb2d637ddb87233e0ce277827 (diff)
downloadlinux-2.6.34-ux500-64565911cdb57c2f512a9715b985b5617402cc67.tar.gz
block: make blktrace use per-cpu buffers for message notes
Currently it uses a single static char array, but that risks being corrupted when multiple users issue message notes at the same time. Make the buffers dynamically allocated when the trace is setup and make them per-cpu instead. The default max message size of 1k is also very large, the interface is mainly for small text notes. So shrink it to 128 bytes. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
-rw-r--r--block/blktrace.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/block/blktrace.c b/block/blktrace.c
index 20e11f354f1..7ae87cc4a16 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -79,13 +79,16 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
{
int n;
va_list args;
- static char bt_msg_buf[BLK_TN_MAX_MSG];
+ char *buf;
+ preempt_disable();
+ buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
va_start(args, fmt);
- n = vscnprintf(bt_msg_buf, BLK_TN_MAX_MSG, fmt, args);
+ n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
va_end(args);
- trace_note(bt, 0, BLK_TN_MESSAGE, bt_msg_buf, n);
+ trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
+ preempt_enable();
}
EXPORT_SYMBOL_GPL(__trace_note_message);
@@ -246,6 +249,7 @@ static void blk_trace_cleanup(struct blk_trace *bt)
debugfs_remove(bt->dropped_file);
blk_remove_tree(bt->dir);
free_percpu(bt->sequence);
+ free_percpu(bt->msg_data);
kfree(bt);
}
@@ -360,6 +364,10 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (!bt->sequence)
goto err;
+ bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG);
+ if (!bt->msg_data)
+ goto err;
+
ret = -ENOENT;
dir = blk_create_tree(buts->name);
if (!dir)
@@ -406,6 +414,7 @@ err:
if (bt->dropped_file)
debugfs_remove(bt->dropped_file);
free_percpu(bt->sequence);
+ free_percpu(bt->msg_data);
if (bt->rchan)
relay_close(bt->rchan);
kfree(bt);