On 10/17/2013 11:25 AM, Josh Triplett wrote:
On Wed, Oct 16, 2013 at 10:23:56PM -0500, Larry Finger wrote:Sparse reports the following: CHECK drivers/staging/rtl8188eu/core/rtw_mlme.c drivers/staging/rtl8188eu/core/rtw_mlme.c:1003:9: warning: context imbalance in 'rtw_free_assoc_resources' - different lock contexts for basic block The code in question is as follows: if (lock_scanned_queue) spin_lock_bh(&(pmlmepriv->scanned_queue.lock)); pwlan = rtw_find_network(&pmlmepriv->scanned_queue, tgt_network->network.MacAddress); if (lock_scanned_queue) spin_unlock_bh(&(pmlmepriv->scanned_queue.lock)); As this fragment uses the identical test to unlock that is used to lock, and the test variable is not touched, I think this is a false indication. I am using version 0.4.4 of sparse.Sparse can't track conditional contexts like this; sparse intentionally complains here that you're running the same basic block (the rtw_find_network call) with and without a lock held. The following workaround works when this is legitimate, though it isn't ideal: if (condition) { lock do_thing unlock } else { do_thing } Ideally, Sparse should be able to track conditional contexts, but that would require some form of abstract evaluation, or as a simplistic hack, looking for identical side-effect-free conditional expressions.
Thanks for the answer, which is about what I expected. Sparse is a great tool, particularly for endian-related issues.
Larry -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
