From: Hans Holmberg Date: Thu, 29 Mar 2018 22:04:58 +0000 (+0200) Subject: lightnvm: pblk: prevent race in pblk_rb_flush_point_set X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=3c05ef115c696392d9703be3fe014100ec77864d;p=openwrt%2Fstaging%2Fblogic.git lightnvm: pblk: prevent race in pblk_rb_flush_point_set Make sure that we are not advancing the sync pointer while we're adding bios to the write buffer entry completion list. This race condition results in bios not completing and was identified by a hang when running xfstest generic/113. Signed-off-by: Hans Holmberg Reviewed-by: Javier González Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe --- diff --git a/drivers/lightnvm/pblk-rb.c b/drivers/lightnvm/pblk-rb.c index 8b1434060fb3..52fdd85dbc97 100644 --- a/drivers/lightnvm/pblk-rb.c +++ b/drivers/lightnvm/pblk-rb.c @@ -355,10 +355,13 @@ static int pblk_rb_flush_point_set(struct pblk_rb *rb, struct bio *bio, struct pblk_rb_entry *entry; unsigned int sync, flush_point; + pblk_rb_sync_init(rb, NULL); sync = READ_ONCE(rb->sync); - if (pos == sync) + if (pos == sync) { + pblk_rb_sync_end(rb, NULL); return 0; + } #ifdef CONFIG_NVM_DEBUG atomic_inc(&rb->inflight_flush_point); @@ -367,8 +370,6 @@ static int pblk_rb_flush_point_set(struct pblk_rb *rb, struct bio *bio, flush_point = (pos == 0) ? (rb->nr_entries - 1) : (pos - 1); entry = &rb->entries[flush_point]; - pblk_rb_sync_init(rb, NULL); - /* Protect flush points */ smp_store_release(&rb->flush_point, flush_point);