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Mon, 27 Feb 2023 05:29:34 -0600 Received: from ediex02.ad.cirrus.com (198.61.84.81) by ediex02.ad.cirrus.com (198.61.84.81) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.25; Mon, 27 Feb 2023 05:29:33 -0600 Received: from ediswmail.ad.cirrus.com (198.61.86.93) by anon-ediex02.ad.cirrus.com (198.61.84.81) with Microsoft SMTP Server id 15.2.1118.25 via Frontend Transport; Mon, 27 Feb 2023 05:29:33 -0600 Received: from edi-sw-dsktp-006.ad.cirrus.com (edi-sw-dsktp-006.ad.cirrus.com [198.90.251.127]) by ediswmail.ad.cirrus.com (Postfix) with ESMTP id 43F282A1; Mon, 27 Feb 2023 11:29:33 +0000 (UTC) From: Richard Fitzgerald To: , , , Subject: [PATCH] soundwire: bus: Fix unbalanced pm_runtime_put() causing usage count underflow Date: Mon, 27 Feb 2023 11:29:33 +0000 Message-ID: <20230227112933.1593997-1-rf@opensource.cirrus.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-Proofpoint-ORIG-GUID: GBWC0_m8lQofO7J-JHQhJm6sDI-NNg1B X-Proofpoint-GUID: GBWC0_m8lQofO7J-JHQhJm6sDI-NNg1B X-Proofpoint-Spam-Reason: safe Message-ID-Hash: 2OORCUKRE6JBRIUACKJ4ACF6W2FOZWT6 X-Message-ID-Hash: 2OORCUKRE6JBRIUACKJ4ACF6W2FOZWT6 X-MailFrom: prvs=74223fc41f=rf@opensource.cirrus.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, patches@opensource.cirrus.com, Richard Fitzgerald X-Mailman-Version: 3.3.8 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: This reverts commit 443a98e649b4 ("soundwire: bus: use pm_runtime_resume_and_get()") Change calls to pm_runtime_resume_and_get() back to pm_runtime_get_sync(). This fixes a usage count underrun caused by doing a pm_runtime_put() even though pm_runtime_resume_and_get() returned an error. The three affected functions ignore -EACCES error from trying to get pm_runtime, and carry on, including a put at the end of the function. But pm_runtime_resume_and_get() does not increment the usage count if it returns an error. So in the -EACCES case you must not call pm_runtime_put(). The documentation for pm_runtime_get_sync() says: "Consider using pm_runtime_resume_and_get() ... as this is likely to result in cleaner code." In this case I don't think it results in cleaner code because the pm_runtime_put() at the end of the function would have to be conditional on the return value from pm_runtime_resume_and_get() at the top of the function. pm_runtime_get_sync() doesn't have this problem because it always increments the count, so always needs a put. The code can just flow through and do the pm_runtime_put() unconditionally. Signed-off-by: Richard Fitzgerald --- drivers/soundwire/bus.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index 76515c33e639..4fd221d0cc81 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -571,9 +571,11 @@ int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val) { int ret; - ret = pm_runtime_resume_and_get(&slave->dev); - if (ret < 0 && ret != -EACCES) + ret = pm_runtime_get_sync(&slave->dev); + if (ret < 0 && ret != -EACCES) { + pm_runtime_put_noidle(&slave->dev); return ret; + } ret = sdw_nread_no_pm(slave, addr, count, val); @@ -595,9 +597,11 @@ int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val) { int ret; - ret = pm_runtime_resume_and_get(&slave->dev); - if (ret < 0 && ret != -EACCES) + ret = pm_runtime_get_sync(&slave->dev); + if (ret < 0 && ret != -EACCES) { + pm_runtime_put_noidle(&slave->dev); return ret; + } ret = sdw_nwrite_no_pm(slave, addr, count, val); @@ -1565,9 +1569,10 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave) sdw_modify_slave_status(slave, SDW_SLAVE_ALERT); - ret = pm_runtime_resume_and_get(&slave->dev); + ret = pm_runtime_get_sync(&slave->dev); if (ret < 0 && ret != -EACCES) { dev_err(&slave->dev, "Failed to resume device: %d\n", ret); + pm_runtime_put_noidle(&slave->dev); return ret; }