[{"id":21874,"web_url":"https://patchwork.libcamera.org/comment/21874/","msgid":"<164026654652.3986460.2907031544807534997@Monstersaurus>","date":"2021-12-23T13:35:46","subject":"Re: [libcamera-devel] [PATCH 2/2] libcamera: pipeline_handler: Make\n\tlock() and unlock() thread-safe","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Quoting Laurent Pinchart (2021-12-23 02:33:31)\n> The PipelineHandler lock() and unlock() functions are documented as\n> thread-safe, but they're not. Fix them using a mutex.\n\nA lock for a lock ...\n\nSeems fine though, but a comment below\n\nReviewed-by: Kieran Bingham \n\n> \n> Signed-off-by: Laurent Pinchart \n> ---\n> include/libcamera/internal/pipeline_handler.h | 2 ++\n> src/libcamera/pipeline_handler.cpp | 5 +++++\n> 2 files changed, 7 insertions(+)\n> \n> diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h\n> index a7331cedfb16..3768bb8f6cb6 100644\n> --- a/include/libcamera/internal/pipeline_handler.h\n> +++ b/include/libcamera/internal/pipeline_handler.h\n> @@ -14,6 +14,7 @@\n> #include \n> #include \n> \n> +#include \n> #include \n> \n> #include \n> @@ -88,6 +89,7 @@ private:\n> \n> const char *name_;\n> \n> + Mutex lock_;\n> bool lockOwner_;\n\nDo we need to comment these at all? lock_ and lockOwner_ while closely\nlinked, could be confusing.\n\nThe lockOwner_ afterall does /not/ have any correspondance to the owner\nof lock_.\n\nA comment above each would probably suffice.\n\n> \n> friend class PipelineHandlerFactory;\n> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp\n> index b2ee4ec0ce87..07d9d387daff 100644\n> --- a/src/libcamera/pipeline_handler.cpp\n> +++ b/src/libcamera/pipeline_handler.cpp\n> @@ -11,6 +11,7 @@\n> #include \n> \n> #include \n> +#include \n> #include \n> \n> #include \n> @@ -155,6 +156,8 @@ MediaDevice *PipelineHandler::acquireMediaDevice(DeviceEnumerator *enumerator,\n> */\n> bool PipelineHandler::lock()\n> {\n> + MutexLocker locker(lock_);\n> +\n> /* Do not allow nested locking in the same libcamera instance. */\n> if (lockOwner_)\n> return false;\n> @@ -183,6 +186,8 @@ bool PipelineHandler::lock()\n> */\n> void PipelineHandler::unlock()\n> {\n> + MutexLocker locker(lock_);\n> +\n> if (lockOwner_)\n> return;\n> \n> -- \n> Regards,\n> \n> Laurent Pinchart\n>","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 7A360BE080\n\tfor ;\n\tThu, 23 Dec 2021 13:35:50 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id DC9A7608FF;\n\tThu, 23 Dec 2021 14:35:49 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id ED40A60115\n\tfor ;\n\tThu, 23 Dec 2021 14:35:48 +0100 (CET)","from pendragon.ideasonboard.com\n\t(cpc89244-aztw30-2-0-cust3082.18-1.cable.virginm.net [86.31.172.11])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 8023D2C5;\n\tThu, 23 Dec 2021 14:35:48 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"eqqM0Dni\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1640266548;\n\tbh=Kql731WWKNNKkcUo6Lcwk6lt0/osPuOlA5/JU5O1cjQ=;\n\th=In-Reply-To:References:Subject:From:To:Date:From;\n\tb=eqqM0DniASrDo1tK2WKUq9ijlvJNSD8ptDXwP2Oam6SYhOqZOB7tomaKCysJt/GIU\n\tZmCPGR6neAcho2ZXj7uYKeiVaqoadu62TXjH+hQuZuKKBHMe8gAENolTddLlKaCVf1\n\t2sEMAkpdsVB2axOTvulG1WvjOVFMUE5D/VkVkMxk=","Content-Type":"text/plain; charset=\"utf-8\"","MIME-Version":"1.0","Content-Transfer-Encoding":"quoted-printable","In-Reply-To":"<20211223023331.13505-3-laurent.pinchart@ideasonboard.com>","References":"<20211223023331.13505-1-laurent.pinchart@ideasonboard.com>\n\t<20211223023331.13505-3-laurent.pinchart@ideasonboard.com>","From":"Kieran Bingham ","To":"Laurent Pinchart ,\n\tlibcamera-devel@lists.libcamera.org","Date":"Thu, 23 Dec 2021 13:35:46 +0000","Message-ID":"<164026654652.3986460.2907031544807534997@Monstersaurus>","User-Agent":"alot/0.10","Subject":"Re: [libcamera-devel] [PATCH 2/2] libcamera: pipeline_handler: Make\n\tlock() and unlock() thread-safe","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}},{"id":21879,"web_url":"https://patchwork.libcamera.org/comment/21879/","msgid":"","date":"2021-12-26T23:04:45","subject":"Re: [libcamera-devel] [PATCH 2/2] libcamera: pipeline_handler: Make\n\tlock() and unlock() thread-safe","submitter":{"id":2,"url":"https://patchwork.libcamera.org/api/people/2/","name":"Laurent Pinchart","email":"laurent.pinchart@ideasonboard.com"},"content":"Hi Kieran,\n\nOn Thu, Dec 23, 2021 at 01:35:46PM +0000, Kieran Bingham wrote:\n> Quoting Laurent Pinchart (2021-12-23 02:33:31)\n> > The PipelineHandler lock() and unlock() functions are documented as\n> > thread-safe, but they're not. Fix them using a mutex.\n> \n> A lock for a lock ...\n> \n> Seems fine though, but a comment below\n> \n> Reviewed-by: Kieran Bingham \n> \n> > Signed-off-by: Laurent Pinchart \n> > ---\n> > include/libcamera/internal/pipeline_handler.h | 2 ++\n> > src/libcamera/pipeline_handler.cpp | 5 +++++\n> > 2 files changed, 7 insertions(+)\n> > \n> > diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h\n> > index a7331cedfb16..3768bb8f6cb6 100644\n> > --- a/include/libcamera/internal/pipeline_handler.h\n> > +++ b/include/libcamera/internal/pipeline_handler.h\n> > @@ -14,6 +14,7 @@\n> > #include \n> > #include \n> > \n> > +#include \n> > #include \n> > \n> > #include \n> > @@ -88,6 +89,7 @@ private:\n> > \n> > const char *name_;\n> > \n> > + Mutex lock_;\n> > bool lockOwner_;\n> \n> Do we need to comment these at all? lock_ and lockOwner_ while closely\n> linked, could be confusing.\n> \n> The lockOwner_ afterall does /not/ have any correspondance to the owner\n> of lock_.\n> \n> A comment above each would probably suffice.\n\nI'll add a comment to lockOwner_ and annotate it with\nLIBCAMERA_TSA_GUARDED_BY(lock_).\n\n> > \n> > friend class PipelineHandlerFactory;\n> > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp\n> > index b2ee4ec0ce87..07d9d387daff 100644\n> > --- a/src/libcamera/pipeline_handler.cpp\n> > +++ b/src/libcamera/pipeline_handler.cpp\n> > @@ -11,6 +11,7 @@\n> > #include \n> > \n> > #include \n> > +#include \n> > #include \n> > \n> > #include \n> > @@ -155,6 +156,8 @@ MediaDevice *PipelineHandler::acquireMediaDevice(DeviceEnumerator *enumerator,\n> > */\n> > bool PipelineHandler::lock()\n> > {\n> > + MutexLocker locker(lock_);\n> > +\n> > /* Do not allow nested locking in the same libcamera instance. */\n> > if (lockOwner_)\n> > return false;\n> > @@ -183,6 +186,8 @@ bool PipelineHandler::lock()\n> > */\n> > void PipelineHandler::unlock()\n> > {\n> > + MutexLocker locker(lock_);\n> > +\n> > if (lockOwner_)\n> > return;\n> >","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id BCAD0BE080\n\tfor ;\n\tSun, 26 Dec 2021 23:04:50 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id E90A760911;\n\tMon, 27 Dec 2021 00:04:49 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 321F6608E6\n\tfor ;\n\tMon, 27 Dec 2021 00:04:48 +0100 (CET)","from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi\n\t[62.78.145.57])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 9CE5DA15;\n\tMon, 27 Dec 2021 00:04:47 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=ideasonboard.com header.i=@ideasonboard.com\n\theader.b=\"M0ifkHpl\"; dkim-atps=neutral","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com;\n\ts=mail; t=1640559887;\n\tbh=2e1p3O7sUidKa3FYrGjQsodbWZ1YOdNKcN7KxIWqKeE=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=M0ifkHplf5kVJmFQp18ZJY8cMP3MYrxayLpoepM0THjPISccsKSKz/4Wk0LLl+CCZ\n\tqWw1Uvx+63KtAUMPJ2l4LQA3S7pBL1BxBKwF1PF2pjoR/lNXkCjQkWPrf7mX+PbthV\n\tQ7d2xEs7n222p/EwDrXAwtGmXVPjqahFP+L1evng=","Date":"Mon, 27 Dec 2021 01:04:45 +0200","From":"Laurent Pinchart ","To":"Kieran Bingham ","Message-ID":"","References":"<20211223023331.13505-1-laurent.pinchart@ideasonboard.com>\n\t<20211223023331.13505-3-laurent.pinchart@ideasonboard.com>\n\t<164026654652.3986460.2907031544807534997@Monstersaurus>","MIME-Version":"1.0","Content-Type":"text/plain; charset=utf-8","Content-Disposition":"inline","In-Reply-To":"<164026654652.3986460.2907031544807534997@Monstersaurus>","Subject":"Re: [libcamera-devel] [PATCH 2/2] libcamera: pipeline_handler: Make\n\tlock() and unlock() thread-safe","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"libcamera-devel@lists.libcamera.org","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "}}]