[PATCH 6.18 0297/1611] ata: libata: Fix ata_exec_internal()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bvanassche@acm.org>

[ Upstream commit aa0ae1c35f7b3e9afed2324bed5f5c87ad55b92c ]

Some but not all ata_exec_internal() calls happen from the context of
the ATA error handler. Commit c0c362b60e25 ("libata: implement cross-port
EH exclusion") added ata_eh_release() and ata_eh_acquire() calls in
ata_exec_internal(). Calling these functions is necessary if the caller
holds the eh_mutex but is not allowed if the caller doesn't hold that
mutex. Fix this by only calling ata_eh_release() and ata_eh_acquire() if
the caller holds the eh_mutex. An example of an indirect caller of
ata_exec_internal() that does not hold the eh_mutex is
ata_host_register().

Fixes: c0c362b60e25 ("libata: implement cross-port EH exclusion")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/ata/libata-core.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 5ee4adc623427c..501330e91f9d37 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1526,6 +1526,7 @@ unsigned int ata_exec_internal(struct ata_device *dev, struct ata_taskfile *tf,
 {
 	struct ata_link *link = dev->link;
 	struct ata_port *ap = link->ap;
+	const bool owns_eh_mutex = ap->host->eh_owner == current;
 	u8 command = tf->command;
 	struct ata_queued_cmd *qc;
 	struct scatterlist sgl;
@@ -1603,11 +1604,25 @@ unsigned int ata_exec_internal(struct ata_device *dev, struct ata_taskfile *tf,
 		}
 	}
 
-	ata_eh_release(ap);
+	if (owns_eh_mutex) {
+		/*
+		 * To prevent that the compiler complains about the
+		 * ata_eh_release() call below.
+		 */
+		__acquire(&ap->host->eh_mutex);
+		ata_eh_release(ap);
+	}
 
 	rc = wait_for_completion_timeout(&wait, msecs_to_jiffies(timeout));
 
-	ata_eh_acquire(ap);
+	if (owns_eh_mutex) {
+		ata_eh_acquire(ap);
+		/*
+		 * To prevent that the compiler complains about the above
+		 * ata_eh_acquire() call.
+		 */
+		__release(&ap->host->eh_mutex);
+	}
 
 	ata_sff_flush_pio_task(ap);
 
-- 
2.53.0