4.4-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 1810f2c44817c74ca3d05d1e3981e3a2e2ceb6f5 ]
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 laurent.fert@intel.com Signed-off-by: Alexander Shishkin alexander.shishkin@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/hwtracing/stm/core.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c index e4fa583b57a6..d4deac108578 100644 --- a/drivers/hwtracing/stm/core.c +++ b/drivers/hwtracing/stm/core.c @@ -817,10 +817,8 @@ 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); @@ -828,6 +826,7 @@ 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); }