From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 412EAC10F0E for ; Fri, 12 Apr 2019 16:22:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0EA8321872 for ; Fri, 12 Apr 2019 16:22:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726711AbfDLQWD (ORCPT ); Fri, 12 Apr 2019 12:22:03 -0400 Received: from mga07.intel.com ([134.134.136.100]:19595 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726624AbfDLQWD (ORCPT ); Fri, 12 Apr 2019 12:22:03 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Apr 2019 09:22:02 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,341,1549958400"; d="scan'208";a="315432864" Received: from unknown (HELO [10.7.153.148]) ([10.7.153.148]) by orsmga005.jf.intel.com with ESMTP; 12 Apr 2019 09:22:02 -0700 Subject: Re: [PATCH v2] media: platform: fix a kernel warning on clk control To: "Herrenschmidt, Benjamin" , "joel@jms.id.au" , "mchehab@kernel.org" , "eajames@linux.ibm.com" , "andrew@aj.id.au" , "hverkuil@xs4all.nl" Cc: "linux-media@vger.kernel.org" , "linux-aspeed@lists.ozlabs.org" References: <20190329212710.5378-1-jae.hyun.yoo@linux.intel.com> <09113211-ef61-2168-cf78-37c76f21edba@xs4all.nl> <9aa895a5184ddd30eb5750e4ec223fd5a5df4a54.camel@amazon.com> From: Jae Hyun Yoo Message-ID: <0a0a8ff6-8ded-9313-a601-754d15f3dc73@linux.intel.com> Date: Fri, 12 Apr 2019 09:22:02 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <9aa895a5184ddd30eb5750e4ec223fd5a5df4a54.camel@amazon.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 4/12/2019 5:17 AM, Herrenschmidt, Benjamin wrote: > On Fri, 2019-04-12 at 13:00 +0200, Hans Verkuil wrote: >> Eddie, can you review this? >> >> Jae Hyun Yoo, for future reference: please add the driver name in the >> subject. >> I.e. something like this: [PATCH v2] media: aspeed: fix a kernel >> warning on clk control >> >> That helps maintainers figuring out who should look at which patch. > > test_bit/clear_bit/set_bit are atomic. The way they are used here is > either a waste of cycles (there's already a lock) or racy. Not too sure > :) Hi Ben, I added spin lock handling too to protect corresponding sequence of turning on and off of the video engine which should be serialized. Even with this protection, clock enable/disable can be double called so I had to add the flag checking. Thanks, Jae > Cheers, > Ben. > >> Regards, >> >> Hans >> >> On 3/29/19 10:27 PM, Jae Hyun Yoo wrote: >>> video_on and video_off functions in the Aspeed video engine driver >>> are >>> being called from multiple contexts without any protection so video >>> clocks >>> can be disabled twice and eventually it causes a kernel warning >>> with stack >>> dump printing out like below: >>> >>> [ 120.034729] WARNING: CPU: 0 PID: 1334 at drivers/clk/clk.c:684 >>> clk_core_unprepare+0x13c/0x170 >>> [ 120.043252] eclk-gate already unprepared >>> [ 120.047283] CPU: 0 PID: 1334 Comm: obmc-ikvm Tainted: >>> G W 5.0.3-b94b74e8b52db91fe4e99e0bb481ec8bf2b5b47c >>> #1 >>> [ 120.058417] Hardware name: Generic DT based system >>> [ 120.063219] Backtrace: >>> [ 120.065787] [<80107cdc>] (dump_backtrace) from [<80107f10>] >>> (show_stack+0x20/0x24) >>> [ 120.073371] r7:803a4ff0 r6:00000009 r5:00000000 r4:96197e1c >>> [ 120.079152] [<80107ef0>] (show_stack) from [<8068f7d8>] >>> (dump_stack+0x20/0x28) >>> [ 120.086479] [<8068f7b8>] (dump_stack) from [<8011604c>] >>> (__warn.part.3+0xb4/0xdc) >>> [ 120.094068] [<80115f98>] (__warn.part.3) from [<801160e0>] >>> (warn_slowpath_fmt+0x6c/0x90) >>> [ 120.102164] r6:000002ac r5:8080c0b8 r4:80a07008 >>> [ 120.106893] [<80116078>] (warn_slowpath_fmt) from [<803a4ff0>] >>> (clk_core_unprepare+0x13c/0x170) >>> [ 120.115686] r3:8080cf8c r2:8080c17c >>> [ 120.119276] r7:97d68e58 r6:9df23200 r5:9668c260 r4:96459260 >>> [ 120.125046] [<803a4eb4>] (clk_core_unprepare) from [<803a707c>] >>> (clk_unprepare+0x34/0x3c) >>> [ 120.133226] r5:9668c260 r4:96459260 >>> [ 120.136932] [<803a7048>] (clk_unprepare) from [<804f34bc>] >>> (aspeed_video_off+0x44/0x48) >>> [ 120.145031] r5:9668c260 r4:9668cbc0 >>> [ 120.148647] [<804f3478>] (aspeed_video_off) from [<804f3fd0>] >>> (aspeed_video_release+0x94/0x118) >>> [ 120.157435] r5:966a0cb8 r4:966a0800 >>> [ 120.161049] [<804f3f3c>] (aspeed_video_release) from >>> [<804d2c58>] (v4l2_release+0xd4/0xe8) >>> [ 120.169404] r7:97d68e58 r6:9d087810 r5:9df23200 r4:966a0b20 >>> [ 120.175168] [<804d2b84>] (v4l2_release) from [<80236224>] >>> (__fput+0x98/0x1c4) >>> [ 120.182316] r5:96698e78 r4:9df23200 >>> [ 120.185994] [<8023618c>] (__fput) from [<802363b8>] >>> (____fput+0x18/0x1c) >>> [ 120.192712] r9:80a0700c r8:801011e4 r7:00000000 r6:80a64bbc >>> r5:961dd560 r4:961dd89c >>> [ 120.200562] [<802363a0>] (____fput) from [<80131c08>] >>> (task_work_run+0x7c/0xa4) >>> [ 120.207994] [<80131b8c>] (task_work_run) from [<80106884>] >>> (do_work_pending+0x4a8/0x578) >>> [ 120.216163] r7:801011e4 r6:80a07008 r5:96197fb0 r4:ffffe000 >>> [ 120.221856] [<801063dc>] (do_work_pending) from [<8010106c>] >>> (slow_work_pending+0xc/0x20) >>> [ 120.230116] Exception stack(0x96197fb0 to 0x96197ff8) >>> [ 120.235254] 7fa0: 00000000 >>> 76ccf094 00000000 00000000 >>> [ 120.243438] 7fc0: 00000008 00a11978 7eab3c30 00000006 00000000 >>> 00000000 475b0fa4 00000000 >>> [ 120.251692] 7fe0: 00000002 7eab3a40 00000000 47720e38 80000010 >>> 00000008 >>> [ 120.258396] r10:00000000 r9:96196000 r8:801011e4 r7:00000006 >>> r6:7eab3c30 r5:00a11978 >>> [ 120.266291] r4:00000008 >>> >>> To prevent this issue, this commit adds spinlock protection and >>> clock >>> status checking logic into the Aspeed video engine driver. >>> >>> Fixes: d2b4387f3bdf ("media: platform: Add Aspeed Video Engine >>> driver") >>> Signed-off-by: Jae Hyun Yoo >>> Cc: Eddie James >>> Cc: Mauro Carvalho Chehab >>> Cc: Joel Stanley >>> Cc: Andrew Jeffery >>> --- >>> drivers/media/platform/aspeed-video.c | 32 >>> ++++++++++++++++++++++++--- >>> 1 file changed, 29 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/media/platform/aspeed-video.c >>> b/drivers/media/platform/aspeed-video.c >>> index 692e08ef38c0..744d22ecc620 100644 >>> --- a/drivers/media/platform/aspeed-video.c >>> +++ b/drivers/media/platform/aspeed-video.c >>> @@ -188,6 +188,7 @@ enum { >>> VIDEO_STREAMING, >>> VIDEO_FRAME_INPRG, >>> VIDEO_STOPPED, >>> + VIDEO_CLOCKS_ON, >>> }; >>> >>> struct aspeed_video_addr { >>> @@ -495,20 +496,30 @@ static void aspeed_video_reset(struct >>> aspeed_video *video) >>> >>> static void aspeed_video_off(struct aspeed_video *video) >>> { >>> + if (!test_bit(VIDEO_CLOCKS_ON, &video->flags)) >>> + return; >>> + >>> aspeed_video_reset(video); >>> >>> /* Turn off the relevant clocks */ >>> clk_disable_unprepare(video->vclk); >>> clk_disable_unprepare(video->eclk); >>> + >>> + clear_bit(VIDEO_CLOCKS_ON, &video->flags); >>> } >>> >>> static void aspeed_video_on(struct aspeed_video *video) >>> { >>> + if (test_bit(VIDEO_CLOCKS_ON, &video->flags)) >>> + return; >>> + >>> /* Turn on the relevant clocks */ >>> clk_prepare_enable(video->eclk); >>> clk_prepare_enable(video->vclk); >>> >>> aspeed_video_reset(video); >>> + >>> + set_bit(VIDEO_CLOCKS_ON, &video->flags); >>> } >>> >>> static void aspeed_video_bufs_done(struct aspeed_video *video, >>> @@ -526,12 +537,14 @@ static void aspeed_video_bufs_done(struct >>> aspeed_video *video, >>> >>> static void aspeed_video_irq_res_change(struct aspeed_video >>> *video) >>> { >>> + spin_lock(&video->lock); >>> dev_dbg(video->dev, "Resolution changed; resetting\n"); >>> >>> set_bit(VIDEO_RES_CHANGE, &video->flags); >>> clear_bit(VIDEO_FRAME_INPRG, &video->flags); >>> >>> aspeed_video_off(video); >>> + spin_unlock(&video->lock); >>> aspeed_video_bufs_done(video, VB2_BUF_STATE_ERROR); >>> >>> schedule_delayed_work(&video->res_work, >>> RESOLUTION_CHANGE_DELAY); >>> @@ -951,9 +964,13 @@ static void aspeed_video_init_regs(struct >>> aspeed_video *video) >>> >>> static void aspeed_video_start(struct aspeed_video *video) >>> { >>> + unsigned long flags; >>> + >>> + spin_lock_irqsave(&video->lock, flags); >>> aspeed_video_on(video); >>> >>> aspeed_video_init_regs(video); >>> + spin_unlock_irqrestore(&video->lock, flags); >>> >>> /* Resolution set to 640x480 if no signal found */ >>> aspeed_video_get_resolution(video); >>> @@ -969,6 +986,9 @@ static void aspeed_video_start(struct >>> aspeed_video *video) >>> >>> static void aspeed_video_stop(struct aspeed_video *video) >>> { >>> + unsigned long flags; >>> + >>> + spin_lock_irqsave(&video->lock, flags); >>> set_bit(VIDEO_STOPPED, &video->flags); >>> cancel_delayed_work_sync(&video->res_work); >>> >>> @@ -982,6 +1002,7 @@ static void aspeed_video_stop(struct >>> aspeed_video *video) >>> >>> video->v4l2_input_status = V4L2_IN_ST_NO_SIGNAL; >>> video->flags = 0; >>> + spin_unlock_irqrestore(&video->lock, flags); >>> } >>> >>> static int aspeed_video_querycap(struct file *file, void *fh, >>> @@ -1319,16 +1340,21 @@ static void >>> aspeed_video_resolution_work(struct work_struct *work) >>> struct delayed_work *dwork = to_delayed_work(work); >>> struct aspeed_video *video = container_of(dwork, struct >>> aspeed_video, >>> res_work); >>> - u32 input_status = video->v4l2_input_status; >>> + unsigned long flags; >>> + u32 input_status; >>> >>> + spin_lock_irqsave(&video->lock, flags); >>> + input_status = video->v4l2_input_status; >>> aspeed_video_on(video); >>> >>> /* Exit early in case no clients remain */ >>> - if (test_bit(VIDEO_STOPPED, &video->flags)) >>> + if (test_bit(VIDEO_STOPPED, &video->flags)) { >>> + spin_unlock_irqrestore(&video->lock, flags); >>> goto done; >>> + } >>> >>> aspeed_video_init_regs(video); >>> - >>> + spin_unlock_irqrestore(&video->lock, flags); >>> aspeed_video_get_resolution(video); >>> >>> if (video->detected_timings.width != video- >>>> active_timings.width || >>>