From: okaya@codeaurora.org To: Vinod Koul <vinod.koul@intel.com> Cc: dmaengine@vger.kernel.org, timur@codeaurora.org, Christopher Covington <cov@codeaurora.org>, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, dmaengine-owner@vger.kernel.org Subject: Re: [PATCH] dmaengine: qcom_hidma: release the descriptor before the callback Date: Mon, 08 Aug 2016 08:10:51 -0400 [thread overview] Message-ID: <001a1ffff4ea639cb94d0dfbcb3e14d1@codeaurora.org> (raw) In-Reply-To: <20160808085155.GX9681@localhost> On 2016-08-08 04:51, Vinod Koul wrote: > >> This patch is needed to fix a race condition as the commit message >> describes. >> The callback is called before returning the descriptor back to free >> pool. >> >> If the client calls free resources, the descriptor that was not >> returned to free pool gets lost due >> to race condition. > > Hmmm, if you have txn's pending and client wants to free up, shouldn't > the pending txn's be cleaned up? Sound like a different bug to me.. > > So if I submit 5 txn's and now want to freeup, will you still leak > descriptors? Doesn't sound as right behaviour to me. > If free is called from the callback, current code will leak the current descriptor where free was called. It will release the other 4. Because of ordering problem, descriptor is not in the active, pending or free pool. I check pending txn by looking at active and queued lists when free is called. After the callback, I put the descriptor back to free pool. At this moment, it is already too late. >> I'll refactor the code after Dave's change for passing the error code >> while calling the >> callback. That will be a different patch anyhow. > > Yes the error reporting is different
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From: okaya@codeaurora.org (okaya at codeaurora.org) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] dmaengine: qcom_hidma: release the descriptor before the callback Date: Mon, 08 Aug 2016 08:10:51 -0400 [thread overview] Message-ID: <001a1ffff4ea639cb94d0dfbcb3e14d1@codeaurora.org> (raw) In-Reply-To: <20160808085155.GX9681@localhost> On 2016-08-08 04:51, Vinod Koul wrote: > >> This patch is needed to fix a race condition as the commit message >> describes. >> The callback is called before returning the descriptor back to free >> pool. >> >> If the client calls free resources, the descriptor that was not >> returned to free pool gets lost due >> to race condition. > > Hmmm, if you have txn's pending and client wants to free up, shouldn't > the pending txn's be cleaned up? Sound like a different bug to me.. > > So if I submit 5 txn's and now want to freeup, will you still leak > descriptors? Doesn't sound as right behaviour to me. > If free is called from the callback, current code will leak the current descriptor where free was called. It will release the other 4. Because of ordering problem, descriptor is not in the active, pending or free pool. I check pending txn by looking at active and queued lists when free is called. After the callback, I put the descriptor back to free pool. At this moment, it is already too late. >> I'll refactor the code after Dave's change for passing the error code >> while calling the >> callback. That will be a different patch anyhow. > > Yes the error reporting is different
next prev parent reply other threads:[~2016-08-08 12:10 UTC|newest] Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-07-14 2:57 [PATCH] dmaengine: qcom_hidma: release the descriptor before the callback Sinan Kaya 2016-07-14 2:57 ` Sinan Kaya 2016-07-16 1:00 ` Sinan Kaya 2016-07-16 1:00 ` Sinan Kaya 2016-07-24 6:24 ` Vinod Koul 2016-07-24 6:24 ` Vinod Koul 2016-07-25 14:19 ` Sinan Kaya 2016-07-25 14:19 ` Sinan Kaya 2016-08-04 12:55 ` Vinod Koul 2016-08-04 12:55 ` Vinod Koul 2016-08-04 12:55 ` Vinod Koul 2016-08-04 14:17 ` Sinan Kaya 2016-08-04 14:17 ` Sinan Kaya 2016-08-04 14:40 ` Russell King - ARM Linux 2016-08-04 14:40 ` Russell King - ARM Linux 2016-08-04 15:27 ` Sinan Kaya 2016-08-04 15:27 ` Sinan Kaya 2016-08-04 15:38 ` Russell King - ARM Linux 2016-08-04 15:38 ` Russell King - ARM Linux 2016-08-04 15:59 ` Lars-Peter Clausen 2016-08-04 15:59 ` Lars-Peter Clausen 2016-08-08 9:08 ` Vinod Koul 2016-08-08 9:08 ` Vinod Koul 2016-08-08 12:25 ` Lars-Peter Clausen 2016-08-08 12:25 ` Lars-Peter Clausen 2016-08-10 17:23 ` Vinod Koul 2016-08-10 17:23 ` Vinod Koul 2016-08-10 17:23 ` Vinod Koul 2016-08-04 16:08 ` Sinan Kaya 2016-08-04 16:08 ` Sinan Kaya 2016-08-04 16:15 ` Lars-Peter Clausen 2016-08-04 16:15 ` Lars-Peter Clausen 2016-08-05 6:32 ` Robert Jarzmik 2016-08-05 6:32 ` Robert Jarzmik 2016-08-05 8:34 ` Lars-Peter Clausen 2016-08-05 8:34 ` Lars-Peter Clausen 2016-08-05 8:34 ` Lars-Peter Clausen 2016-08-05 15:17 ` Sinan Kaya 2016-08-05 15:17 ` Sinan Kaya 2016-08-08 9:02 ` Vinod Koul 2016-08-08 9:02 ` Vinod Koul 2016-08-08 14:45 ` Sinan Kaya 2016-08-08 14:45 ` Sinan Kaya 2016-08-10 17:28 ` Vinod Koul 2016-08-10 17:28 ` Vinod Koul 2016-08-10 17:28 ` Vinod Koul 2016-08-10 17:31 ` Sinan Kaya 2016-08-10 17:31 ` Sinan Kaya 2016-08-10 17:31 ` Sinan Kaya 2016-08-19 2:48 ` Vinod Koul 2016-08-19 2:48 ` Vinod Koul 2016-08-19 3:26 ` Sinan Kaya 2016-08-19 3:26 ` Sinan Kaya 2016-08-19 3:26 ` Sinan Kaya 2016-08-19 3:42 ` Vinod Koul 2016-08-19 3:42 ` Vinod Koul 2016-08-19 3:48 ` Sinan Kaya 2016-08-19 3:48 ` Sinan Kaya 2016-08-19 5:52 ` Vinod Koul 2016-08-19 5:52 ` Vinod Koul 2016-08-19 11:13 ` okaya 2016-08-19 11:13 ` okaya at codeaurora.org 2016-08-19 11:13 ` okaya 2016-08-19 17:02 ` Vinod Koul 2016-08-19 17:02 ` Vinod Koul 2016-08-19 17:02 ` Vinod Koul 2016-08-19 17:21 ` Sinan Kaya 2016-08-19 17:21 ` Sinan Kaya 2016-08-19 17:21 ` Sinan Kaya 2016-08-22 6:08 ` Vinod Koul 2016-08-22 6:08 ` Vinod Koul 2016-08-22 6:08 ` Vinod Koul 2016-08-22 13:27 ` Sinan Kaya 2016-08-22 13:27 ` Sinan Kaya 2016-08-22 17:00 ` Vinod Koul 2016-08-22 17:00 ` Vinod Koul 2016-08-08 8:51 ` Vinod Koul 2016-08-08 8:51 ` Vinod Koul 2016-08-08 12:10 ` okaya [this message] 2016-08-08 12:10 ` okaya at codeaurora.org
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