From: Ingo Molnar <mingo@elte.hu>
To: Jens Axboe <axboe@suse.de>
Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>
Subject: [patch] fix diskstats_show() accounting with PREEMPT
Date: Tue, 21 Sep 2004 17:37:50 +0200 [thread overview]
Message-ID: <20040921153750.GA21449@elte.hu> (raw)
there is another (minor) bug that the smp_processor_id() debugger
unearthed: diskstats_show() could do a disk_round_stats() ->
disk_stat_add() with preemption enabled - possibly resulting in losing
statistics updates.
Patch attached. (The overwhelming majority of disk_stat_add() callers
have preemption disabled so fixing the remaining two was the best.)
Ingo
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--- linux/drivers/block/genhd.c.orig
+++ linux/drivers/block/genhd.c
@@ -365,7 +365,9 @@ static ssize_t disk_size_read(struct gen
static ssize_t disk_stats_read(struct gendisk * disk, char *page)
{
+ preempt_disable();
disk_round_stats(disk);
+ preempt_enable();
return sprintf(page,
"%8u %8u %8llu %8u "
"%8u %8u %8llu %8u "
@@ -494,7 +496,9 @@ static int diskstats_show(struct seq_fil
"\n\n");
*/
+ preempt_disable();
disk_round_stats(gp);
+ preempt_enable();
seq_printf(s, "%4d %4d %s %u %u %llu %u %u %u %llu %u %u %u %u\n",
gp->major, n + gp->first_minor, disk_name(gp, n, buf),
disk_stat_read(gp, reads), disk_stat_read(gp, read_merges),
next reply other threads:[~2004-09-21 15:36 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-21 15:37 Ingo Molnar [this message]
2004-09-22 10:55 ` [patch] fix diskstats_show() accounting with PREEMPT Jens Axboe
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