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([59.16.200.168]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-746e341039dsm701253b3a.103.2025.05.28.01.01.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 May 2025 01:01:24 -0700 (PDT) From: Gyeyoung Baek To: Jonathan Cameron Cc: David Lechner , =?UTF-8?q?Nuno=20S=C3=A1?= , Andy Shevchenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Gyeyoung Baek Subject: [PATCH v2] iio: trigger: Avoid data race Date: Wed, 28 May 2025 17:01:19 +0900 Message-ID: <20250528080119.9380-1-gye976@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit A data race could occur between `atomic_read()` and `atomic_set()`. Use `atomic_cmpxchg_relaxed()` to group them atomically. Previously the main logic was executed when `use_count` was 0. Now it returns early when `use_count` was not 0. Signed-off-by: Gyeyoung Baek --- Changelog: v2: - Edit commit message. - Separate variable declaration from logic. (Andy) --- drivers/iio/industrialio-trigger.c | 32 +++++++++++++++--------------- 1 file changed, 16 insertions(+), 16 deletions(-) diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c index 54416a384232..fc799910c74d 100644 --- a/drivers/iio/industrialio-trigger.c +++ b/drivers/iio/industrialio-trigger.c @@ -196,15 +196,15 @@ void iio_trigger_poll(struct iio_trigger *trig) { int i; - if (!atomic_read(&trig->use_count)) { - atomic_set(&trig->use_count, CONFIG_IIO_CONSUMERS_PER_TRIGGER); + if (atomic_cmpxchg_relaxed(&trig->use_count, 0, + CONFIG_IIO_CONSUMERS_PER_TRIGGER)) + return; - for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) { - if (trig->subirqs[i].enabled) - generic_handle_irq(trig->subirq_base + i); - else - iio_trigger_notify_done_atomic(trig); - } + for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) { + if (trig->subirqs[i].enabled) + generic_handle_irq(trig->subirq_base + i); + else + iio_trigger_notify_done_atomic(trig); } } EXPORT_SYMBOL(iio_trigger_poll); @@ -227,15 +227,15 @@ void iio_trigger_poll_nested(struct iio_trigger *trig) { int i; - if (!atomic_read(&trig->use_count)) { - atomic_set(&trig->use_count, CONFIG_IIO_CONSUMERS_PER_TRIGGER); + if (atomic_cmpxchg_relaxed(&trig->use_count, 0, + CONFIG_IIO_CONSUMERS_PER_TRIGGER)) + return; - for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) { - if (trig->subirqs[i].enabled) - handle_nested_irq(trig->subirq_base + i); - else - iio_trigger_notify_done(trig); - } + for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) { + if (trig->subirqs[i].enabled) + handle_nested_irq(trig->subirq_base + i); + else + iio_trigger_notify_done(trig); } } EXPORT_SYMBOL(iio_trigger_poll_nested); -- 2.43.0 From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f176.google.com (mail-pl1-f176.google.com [209.85.214.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1D84C262A6; Wed, 28 May 2025 14:57:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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([39.120.225.141]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-234d2fe1ec1sm12971185ad.61.2025.05.28.07.57.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 May 2025 07:57:08 -0700 (PDT) From: Gyeyoung Baek To: Jonathan Cameron Cc: David Lechner , =?UTF-8?q?Nuno=20S=C3=A1?= , Andy Shevchenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Gyeyoung Baek Subject: [PATCH v3] iio: trigger: Avoid data race Date: Wed, 28 May 2025 23:56:48 +0900 Message-ID: <20250528080119.9380-1-gye976@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-ID: <20250528145648.puTzwVz0ui-4FeoUrMKBPfq9aNfc8m7ZQ8-jOSPrSbo@z> A data race could occur between `atomic_read()` and `atomic_set()`. Use `atomic_cmpxchg_relaxed()` to group them atomically. Previously the main logic was executed when `use_count` was 0. Now it returns early when `use_count` was not 0. Fixes: a1a8e1dc111d ("iio:trigger: Fix use_count race condition") Reviewed-by: Andy Shevchenko Signed-off-by: Gyeyoung Baek --- Changelog: v3: - Add Fixes tag. v2: - Edit commit message. - Separate variable declaration from logic. --- drivers/iio/industrialio-trigger.c | 32 +++++++++++++++--------------- 1 file changed, 16 insertions(+), 16 deletions(-) diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c index 54416a384232..fc799910c74d 100644 --- a/drivers/iio/industrialio-trigger.c +++ b/drivers/iio/industrialio-trigger.c @@ -196,15 +196,15 @@ void iio_trigger_poll(struct iio_trigger *trig) { int i; - if (!atomic_read(&trig->use_count)) { - atomic_set(&trig->use_count, CONFIG_IIO_CONSUMERS_PER_TRIGGER); + if (atomic_cmpxchg_relaxed(&trig->use_count, 0, + CONFIG_IIO_CONSUMERS_PER_TRIGGER)) + return; - for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) { - if (trig->subirqs[i].enabled) - generic_handle_irq(trig->subirq_base + i); - else - iio_trigger_notify_done_atomic(trig); - } + for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) { + if (trig->subirqs[i].enabled) + generic_handle_irq(trig->subirq_base + i); + else + iio_trigger_notify_done_atomic(trig); } } EXPORT_SYMBOL(iio_trigger_poll); @@ -227,15 +227,15 @@ void iio_trigger_poll_nested(struct iio_trigger *trig) { int i; - if (!atomic_read(&trig->use_count)) { - atomic_set(&trig->use_count, CONFIG_IIO_CONSUMERS_PER_TRIGGER); + if (atomic_cmpxchg_relaxed(&trig->use_count, 0, + CONFIG_IIO_CONSUMERS_PER_TRIGGER)) + return; - for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) { - if (trig->subirqs[i].enabled) - handle_nested_irq(trig->subirq_base + i); - else - iio_trigger_notify_done(trig); - } + for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) { + if (trig->subirqs[i].enabled) + handle_nested_irq(trig->subirq_base + i); + else + iio_trigger_notify_done(trig); } } EXPORT_SYMBOL(iio_trigger_poll_nested); -- 2.43.0