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Wed, 7 Mar 2018 23:59:05 -0500 Received: from mail-sn1nam01on0102.outbound.protection.outlook.com ([104.47.32.102]:61147 "EHLO NAM01-SN1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S935347AbeCHE64 (ORCPT ); Wed, 7 Mar 2018 23:58:56 -0500 From: Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" CC: Shuah Khan , Sylwester Nawrocki , Mauro Carvalho Chehab , Sasha Levin Subject: [PATCH AUTOSEL for 4.14 34/67] media: s5p-mfc: Fix lock contention - request_firmware() once Thread-Topic: [PATCH AUTOSEL for 4.14 34/67] media: s5p-mfc: Fix lock contention - request_firmware() once Thread-Index: AQHTtpn/aEWbK2A190ix6vbZjYDghw== Date: Thu, 8 Mar 2018 04:57:46 +0000 Message-ID: <20180308045641.7814-34-alexander.levin@microsoft.com> References: <20180308045641.7814-1-alexander.levin@microsoft.com> In-Reply-To: <20180308045641.7814-1-alexander.levin@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [52.168.54.252] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DM5PR2101MB1015;7:jl2Fb9AOGp+zvVB9CDIesNRGwegbTft5V1o++YlAWvvnDeIu9IWJTx3z9VmnK2pGqmAlrAL5aKqjVOw3ce1Te8a+oCiRW8OMyn6Mf1RdtVRSQ6jUF5KomW/ZbC6/WkueA/dAr/MlBL9QlDWYgQozgjX1BB00EMv1Q1SpAda0LNzYt9uEu+jVAuSSSphjcaKv2IIA1P1ECekKtEWy24izaSVsH2BW4cMt7FwWj9NHLcenYi/sg9lWinrTe0EWzM/m;20:rTZJ5T5xSgsM7dn5uEhXtc96br17Lokq2IgA8qJgDuFSqBi+nrlxn9hlOPu/f8w9t7QYJdnPLmDPdybMgd9JtDbWHDR6f8MArrjuvQljN0WbwnsWUEeVi2y+YjtlPWkKtyYNW2SYrnYb3fBt7a5Z2XlGiVarW+gmq9qg6Fm3U/4= x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 0bf3e75f-6635-483b-abee-08d584b14aff x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(48565401081)(5600026)(4604075)(3008032)(4534165)(4627221)(201703031133081)(201702281549075)(2017052603328)(7193020);SRVR:DM5PR2101MB1015; 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x-microsoft-antispam-message-info: jW86nKNw+moEaw3Mn/IwxHOrqB+BZghx/cwVfqvfja1d4XFnDSUTLntDKXDioRf+roi7hIN933dpww4vCHa8klHAsuFTp0H95uGWgo0b4Uj9G+eMgLrXvUljOHRcvI8WM05wc/rRHxA1eBIQXcHasMmBPMjbh2WeskzAOACt1omW9r030BL6IdOTiBLtbxfp5kcl+NefMbd6WSPgTBroRhCUeyLJrix/XTqwDMhIDAOa2BBJ5QsmLJhAuYL8P52vVvAuc3oWGsy6kH+XGgqZE2ozuovxUoQqGaMyLz2+n3B6wmbnTGh00znOZvNklxa/FhRJUvkAk3v6g2DLng8ujg== spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: 0bf3e75f-6635-483b-abee-08d584b14aff X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Mar 2018 04:57:46.4692 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB1015 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Shuah Khan [ Upstream commit f45ce9877561044090010e0eb0fad644232ded04 ] Driver calls request_firmware() whenever the device is opened for the first time. As the device gets opened and closed, dev->num_inst =3D=3D 1 is true several times. This is not necessary since the firmware is saved in the fw_buf. s5p_mfc_load_firmware() copies the buffer returned by the request_firmware() to dev->fw_buf. fw_buf sticks around until it gets released from s5p_mfc_remove(), hence there is no need to keep requesting firmware and copying it to fw_buf. This might have been overlooked when changes are made to free fw_buf from the device release interface s5p_mfc_release(). Fix s5p_mfc_load_firmware() to call request_firmware() once and keep state. Change _probe() to load firmware once fw_buf has been allocated. s5p_mfc_open() and it continues to call s5p_mfc_load_firmware() and init hardware which is the step where firmware is written to the device. This addresses the mfc_mutex contention due to repeated request_firmware() calls from open() in the following circular locking warning: [ 552.194115] qtdemux0:sink/2710 is trying to acquire lock: [ 552.199488] (&dev->mfc_mutex){+.+.}, at: [] s5p_mfc_mmap+0x28= /0xd4 [s5p_mfc] [ 552.207459] but task is already holding lock: [ 552.213264] (&mm->mmap_sem){++++}, at: [] vm_mmap_pgoff+0x44/= 0xb8 [ 552.220284] which lock already depends on the new lock. [ 552.228429] the existing dependency chain (in reverse order) is: [ 552.235881] -> #2 (&mm->mmap_sem){++++}: [ 552.241259] __might_fault+0x80/0xb0 [ 552.245331] filldir64+0xc0/0x2f8 [ 552.249144] call_filldir+0xb0/0x14c [ 552.253214] ext4_readdir+0x768/0x90c [ 552.257374] iterate_dir+0x74/0x168 [ 552.261360] SyS_getdents64+0x7c/0x1a0 [ 552.265608] ret_fast_syscall+0x0/0x28 [ 552.269850] -> #1 (&type->i_mutex_dir_key#2){++++}: [ 552.276180] down_read+0x48/0x90 [ 552.279904] lookup_slow+0x74/0x178 [ 552.283889] walk_component+0x1a4/0x2e4 [ 552.288222] link_path_walk+0x174/0x4a0 [ 552.292555] path_openat+0x68/0x944 [ 552.296541] do_filp_open+0x60/0xc4 [ 552.300528] file_open_name+0xe4/0x114 [ 552.304772] filp_open+0x28/0x48 [ 552.308499] kernel_read_file_from_path+0x30/0x78 [ 552.313700] _request_firmware+0x3ec/0x78c [ 552.318291] request_firmware+0x3c/0x54 [ 552.322642] s5p_mfc_load_firmware+0x54/0x150 [s5p_mfc] [ 552.328358] s5p_mfc_open+0x4e4/0x550 [s5p_mfc] [ 552.333394] v4l2_open+0xa0/0x104 [videodev] [ 552.338137] chrdev_open+0xa4/0x18c [ 552.342121] do_dentry_open+0x208/0x310 [ 552.346454] path_openat+0x28c/0x944 [ 552.350526] do_filp_open+0x60/0xc4 [ 552.354512] do_sys_open+0x118/0x1c8 [ 552.358586] ret_fast_syscall+0x0/0x28 [ 552.362830] -> #0 (&dev->mfc_mutex){+.+.}: -> #0 (&dev->mfc_mutex){+.+.}: [ 552.368379] lock_acquire+0x6c/0x88 [ 552.372364] __mutex_lock+0x68/0xa34 [ 552.376437] mutex_lock_interruptible_nested+0x1c/0x24 [ 552.382086] s5p_mfc_mmap+0x28/0xd4 [s5p_mfc] [ 552.386939] v4l2_mmap+0x54/0x88 [videodev] [ 552.391601] mmap_region+0x3a8/0x638 [ 552.395673] do_mmap+0x330/0x3a4 [ 552.399400] vm_mmap_pgoff+0x90/0xb8 [ 552.403472] SyS_mmap_pgoff+0x90/0xc0 [ 552.407632] ret_fast_syscall+0x0/0x28 [ 552.411876] other info that might help us debug this: [ 552.419848] Chain exists of: &dev->mfc_mutex --> &type->i_mutex_dir_key#2 --> &mm->mmap= _sem [ 552.431200] Possible unsafe locking scenario: [ 552.437092] CPU0 CPU1 [ 552.441598] ---- ---- [ 552.446104] lock(&mm->mmap_sem); [ 552.449484] lock(&type->i_mutex_dir_key#2= ); [ 552.456329] lock(&mm->mmap_sem); [ 552.462222] lock(&dev->mfc_mutex); [ 552.465775] *** DEADLOCK *** Signed-off-by: Shuah Khan Signed-off-by: Sylwester Nawrocki Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Sasha Levin --- drivers/media/platform/s5p-mfc/s5p_mfc.c | 6 ++++++ drivers/media/platform/s5p-mfc/s5p_mfc_common.h | 3 +++ drivers/media/platform/s5p-mfc/s5p_mfc_ctrl.c | 5 +++++ 3 files changed, 14 insertions(+) diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc.c b/drivers/media/platf= orm/s5p-mfc/s5p_mfc.c index 1afde5021ca6..8e9531f7f83f 100644 --- a/drivers/media/platform/s5p-mfc/s5p_mfc.c +++ b/drivers/media/platform/s5p-mfc/s5p_mfc.c @@ -1315,6 +1315,12 @@ static int s5p_mfc_probe(struct platform_device *pde= v) goto err_dma; } =20 + /* + * Load fails if fs isn't mounted. Try loading anyway. + * _open() will load it, it it fails now. Ignore failure. + */ + s5p_mfc_load_firmware(dev); + mutex_init(&dev->mfc_mutex); init_waitqueue_head(&dev->queue); dev->hw_lock =3D 0; diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc_common.h b/drivers/medi= a/platform/s5p-mfc/s5p_mfc_common.h index 4220914529b2..76119a8cc477 100644 --- a/drivers/media/platform/s5p-mfc/s5p_mfc_common.h +++ b/drivers/media/platform/s5p-mfc/s5p_mfc_common.h @@ -290,6 +290,8 @@ struct s5p_mfc_priv_buf { * @mfc_cmds: cmd structure holding HW commands function pointers * @mfc_regs: structure holding MFC registers * @fw_ver: loaded firmware sub-version + * @fw_get_done flag set when request_firmware() is complete and + * copied into fw_buf * risc_on: flag indicates RISC is on or off * */ @@ -336,6 +338,7 @@ struct s5p_mfc_dev { struct s5p_mfc_hw_cmds *mfc_cmds; const struct s5p_mfc_regs *mfc_regs; enum s5p_mfc_fw_ver fw_ver; + bool fw_get_done; bool risc_on; /* indicates if RISC is on or off */ }; =20 diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc_ctrl.c b/drivers/media/= platform/s5p-mfc/s5p_mfc_ctrl.c index 69ef9c23a99a..d94e59e79fe9 100644 --- a/drivers/media/platform/s5p-mfc/s5p_mfc_ctrl.c +++ b/drivers/media/platform/s5p-mfc/s5p_mfc_ctrl.c @@ -55,6 +55,9 @@ int s5p_mfc_load_firmware(struct s5p_mfc_dev *dev) * into kernel. */ mfc_debug_enter(); =20 + if (dev->fw_get_done) + return 0; + for (i =3D MFC_FW_MAX_VERSIONS - 1; i >=3D 0; i--) { if (!dev->variant->fw_name[i]) continue; @@ -82,6 +85,7 @@ int s5p_mfc_load_firmware(struct s5p_mfc_dev *dev) } memcpy(dev->fw_buf.virt, fw_blob->data, fw_blob->size); wmb(); + dev->fw_get_done =3D true; release_firmware(fw_blob); mfc_debug_leave(); return 0; @@ -93,6 +97,7 @@ int s5p_mfc_release_firmware(struct s5p_mfc_dev *dev) /* Before calling this function one has to make sure * that MFC is no longer processing */ s5p_mfc_release_priv_buf(dev, &dev->fw_buf); + dev->fw_get_done =3D false; return 0; } =20 --=20 2.14.1