linux-kernel - [PATCH 4/6] staging: vchiq_core: Return -EINTR when bulk transfers are interrupted

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Message-ID: <20240918163100.870596-5-umang.jain@ideasonboard.com>
Date: Wed, 18 Sep 2024 22:00:58 +0530
From: Umang Jain <umang.jain@...asonboard.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>
Cc: linux-rpi-kernel@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-staging@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Kieran Bingham <kieran.bingham@...asonboard.com>,
	Arnd Bergmann <arnd@...db.de>,
	Stefan Wahren <wahrenst@....net>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Nicolas Saenz Julienne <nsaenz@...nel.org>,
	Umang Jain <umang.jain@...asonboard.com>
Subject: [PATCH 4/6] staging: vchiq_core: Return -EINTR when bulk transfers are interrupted

Bulk transfers for various VCHIQ modes use mutex_lock_killable() and
wait_for_completion_killable() variations. Currently, -EAGAIN is
returned if these are interrupted by a fatal signal.

-EAGAIN may mislead the caller into thinking the operation can be
retried, while in reality, the process has received a fatal signal
and is terminating. Therefore, we should update the return value to
align with what these killable functions would return, specifically
-EINTR (Interrupted system call).

Signed-off-by: Umang Jain <umang.jain@...asonboard.com>
---
 .../vc04_services/interface/vchiq_arm/vchiq_arm.c    |  8 ++++----
 .../vc04_services/interface/vchiq_arm/vchiq_core.c   | 12 ++++++------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index 661b3a9a8280..d5b23f3fee87 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -870,11 +870,11 @@ vchiq_bulk_transmit(struct vchiq_instance *instance, unsigned int handle, const
 		}
 
 		/*
-		 * vchiq_*_bulk_transfer() may return -EAGAIN, so we need
+		 * vchiq_*_bulk_transfer() may return -EINTR, so we need
 		 * to implement a retry mechanism since this function is
 		 * supposed to block until queued
 		 */
-		if (ret != -EAGAIN)
+		if (ret != -EINTR)
 			break;
 
 		msleep(1);
@@ -906,11 +906,11 @@ int vchiq_bulk_receive(struct vchiq_instance *instance, unsigned int handle,
 		}
 
 		/*
-		 * vchiq_*_bulk_transfer() may return -EAGAIN, so we need
+		 * vchiq_*_bulk_transfer() may return -EINTR, so we need
 		 * to implement a retry mechanism since this function is
 		 * supposed to block until queued
 		 */
-		if (ret != -EAGAIN)
+		if (ret != -EINTR)
 			break;
 
 		msleep(1);
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
index d7b22e37c2ff..426e729b71ee 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_core.c
@@ -2689,16 +2689,16 @@ vchiq_bulk_xfer_queue_msg_killable(struct vchiq_service *service,
 		&service->bulk_tx : &service->bulk_rx;
 
 	if (mutex_lock_killable(&service->bulk_mutex))
-		return -EAGAIN;
+		return -EINTR;
 
 	if (queue->local_insert == queue->remove + VCHIQ_NUM_SERVICE_BULKS) {
 		VCHIQ_SERVICE_STATS_INC(service, bulk_stalls);
 		do {
 			mutex_unlock(&service->bulk_mutex);
 			if (wait_for_completion_killable(&service->bulk_remove_event))
-				return -EAGAIN;
+				return -EINTR;
 			if (mutex_lock_killable(&service->bulk_mutex))
-				return -EAGAIN;
+				return -EINTR;
 		} while (queue->local_insert == queue->remove +
 				VCHIQ_NUM_SERVICE_BULKS);
 	}
@@ -2729,7 +2729,7 @@ vchiq_bulk_xfer_queue_msg_killable(struct vchiq_service *service,
 	 * claim it here to ensure that isn't happening
 	 */
 	if (mutex_lock_killable(&state->slot_mutex)) {
-		status = -EAGAIN;
+		status = -EINTR;
 		goto cancel_bulk_error_exit;
 	}
 
@@ -2764,7 +2764,7 @@ vchiq_bulk_xfer_queue_msg_killable(struct vchiq_service *service,
         if (bulk_waiter) {
                 bulk_waiter->bulk = bulk;
 		if (wait_for_completion_killable(&bulk_waiter->event))
-                        status = -EAGAIN;
+			status = -EINTR;
                 else if (bulk_waiter->actual == VCHIQ_BULK_ACTUAL_ABORTED)
                         status = -EINVAL;
         }
@@ -3203,7 +3203,7 @@ vchiq_bulk_xfer_waiting(struct vchiq_instance *instance,
 	status = 0;
 
 	if (wait_for_completion_killable(&bulk_waiter->event))
-		return -EAGAIN;
+		return -EINTR;
 	else if (bulk_waiter->actual == VCHIQ_BULK_ACTUAL_ABORTED)
 		return -EINVAL;
 
-- 
2.45.2