From: Alexander Shishkin Date: Mon, 15 Feb 2016 17:12:05 +0000 (+0200) Subject: stm class: Fix unlocking braino in the error path X-Git-Tag: firefly_0821_release~176^2~4^2~44^2~93 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=1f6037f5220b05dc3dda8d917d9c57fc29efa0ea;p=firefly-linux-kernel-4.4.55.git stm class: Fix unlocking braino in the error path If an illegal attempt is made to unlink stm source device from an stm device, the stm device's link spinlock mistakenly remains locked. While this really shouldn't happen (there's a warning in place), the locking should remain in order so that we can still recover from this situation if it indeed does happen. This patch unifies the unlocking in the exit path of __stm_source_link_drop() to fix this. Reported-by: Laurent Fert Signed-off-by: Alexander Shishkin Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 1810f2c44817c74ca3d05d1e3981e3a2e2ceb6f5) --- diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c index 1f2b7b47692d..7aaed081fbf9 100644 --- a/drivers/hwtracing/stm/core.c +++ b/drivers/hwtracing/stm/core.c @@ -816,10 +816,8 @@ static void __stm_source_link_drop(struct stm_source_device *src, spin_lock(&stm->link_lock); spin_lock(&src->link_lock); link = srcu_dereference_check(src->link, &stm_source_srcu, 1); - if (WARN_ON_ONCE(link != stm)) { - spin_unlock(&src->link_lock); - return; - } + if (WARN_ON_ONCE(link != stm)) + goto unlock; stm_output_free(link, &src->output); list_del_init(&src->link_entry); @@ -827,6 +825,7 @@ static void __stm_source_link_drop(struct stm_source_device *src, stm_put_device(link); rcu_assign_pointer(src->link, NULL); +unlock: spin_unlock(&src->link_lock); spin_unlock(&stm->link_lock); }