s390/dasd: protect device queue against concurrent access
In dasd_profile_start() the amount of requests on the device queue are counted. The access to the device queue is unprotected against concurrent access. With a lot of parallel I/O, especially with alias devices enabled, the device queue can change while dasd_profile_start() is accessing the queue. In the worst case this leads to a kernel panic due to incorrect pointer accesses. Fix this by taking the device lock before accessing the queue and counting the requests. Additionally the check for a valid profile data pointer can be done earlier to avoid unnecessary locking in a hot path. Cc: <stable@vger.kernel.org> Fixes: 4fa52aa7 ("[S390] dasd: add enhanced DASD statistics interface") Reviewed-by:Stefan Haberland <sth@linux.ibm.com> Signed-off-by:
Jan Höppner <hoeppner@linux.ibm.com> Signed-off-by:
Stefan Haberland <sth@linux.ibm.com> Link: https://lore.kernel.org/r/20231025132437.1223363-3-sth@linux.ibm.com Signed-off-by:
Jens Axboe <axboe@kernel.dk>
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5029c5e4
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