Commit 7f5562d5 authored by Jens Axboe's avatar Jens Axboe

blk-mq-tag: check for NULL rq when iterating tags

Since we introduced blk-mq-sched, the tags->rqs[] array has been
dynamically assigned. So we need to check for NULL when iterating,
since there's a window of time where the bit is set, but we haven't
dynamically assigned the tags->rqs[] array position yet.

This is perfectly safe, since the memory backing of the request is
never going away while the device is alive.
Reviewed-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 62d20aa6
......@@ -214,7 +214,11 @@ static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
bitnr += tags->nr_reserved_tags;
rq = tags->rqs[bitnr];
if (rq->q == hctx->queue)
/*
* We can hit rq == NULL here, because the tagging functions
* test and set the bit before assining ->rqs[].
*/
if (rq && rq->q == hctx->queue)
iter_data->fn(hctx, rq, iter_data->data, reserved);
return true;
}
......@@ -248,9 +252,15 @@ static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
if (!reserved)
bitnr += tags->nr_reserved_tags;
rq = tags->rqs[bitnr];
/*
* We can hit rq == NULL here, because the tagging functions
* test and set the bit before assining ->rqs[].
*/
rq = tags->rqs[bitnr];
if (rq)
iter_data->fn(rq, iter_data->data, reserved);
return true;
}
......
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