Subject: + lib-percpu_counterc-fix-__percpu_counter_add.patch added to -mm tree To: tom.leiming@xxxxxxxxx,axboe@xxxxxxxxx,fan.du@xxxxxxxxxxxxx,paul.gortmaker@xxxxxxxxxxxxx,shli@xxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Mon, 13 Jan 2014 13:39:52 -0800 The patch titled Subject: lib/percpu_counter.c: fix __percpu_counter_add has been added to the -mm tree. Its filename is lib-percpu_counterc-fix-__percpu_counter_add.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/lib-percpu_counterc-fix-__percpu_counter_add.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/lib-percpu_counterc-fix-__percpu_counter_add.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Ming Lei <tom.leiming@xxxxxxxxx> Subject: lib/percpu_counter.c: fix __percpu_counter_add __percpu_counter_add() may be called in softirq/hardirq handler (such as, blk_mq_queue_exit() is typically called in hardirq/softirq handler), so we need to call this_cpu_add()(irq safe helper) to update percpu counter, otherwise counts may be lost. The patch fixes problem that 'rmmod null_blk' hangs in blk_cleanup_queue() because of miscounting of request_queue->mq_usage_counter. This patch is the v1 of previous one of "lib/percpu_counter.c: disable local irq when updating percpu couter", and takes Andrew's approach which may be more efficient for ARCHs(x86, s390) that have optimized this_cpu_add(). Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx> Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx> Cc: Shaohua Li <shli@xxxxxxxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Cc: Fan Du <fan.du@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/percpu_counter.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN lib/percpu_counter.c~lib-percpu_counterc-fix-__percpu_counter_add lib/percpu_counter.c --- a/lib/percpu_counter.c~lib-percpu_counterc-fix-__percpu_counter_add +++ a/lib/percpu_counter.c @@ -82,10 +82,10 @@ void __percpu_counter_add(struct percpu_ unsigned long flags; raw_spin_lock_irqsave(&fbc->lock, flags); fbc->count += count; + __this_cpu_sub(*fbc->counters, count); raw_spin_unlock_irqrestore(&fbc->lock, flags); - __this_cpu_write(*fbc->counters, 0); } else { - __this_cpu_write(*fbc->counters, count); + this_cpu_add(*fbc->counters, amount); } preempt_enable(); } _ Patches currently in -mm which might be from tom.leiming@xxxxxxxxx are lib-percpu_counterc-fix-__percpu_counter_add.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html