This is a note to let you know that I've just added the patch titled dmaengine: idxd: fix missed completion on abort path to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: dmaengine-idxd-fix-missed-completion-on-abort-path.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit e1d11e16425fd96b8327ccdac2e206ec4af3f79d Author: Dave Jiang <dave.jiang@xxxxxxxxx> Date: Wed Dec 8 10:01:27 2021 -0700 dmaengine: idxd: fix missed completion on abort path [ Upstream commit 8affd8a4b5ce356c8900cfb037674f3a4a11fbdb ] Ming reported that with the abort path of the descriptor submission, there can be a window where a completed descriptor can be missed to be completed by the irq completion thread: CPU A CPU B Submit (successful) Submit (fail) irq_process_work_list() // empty llist_abort_desc() // remove all descs from pending list irq_process_pending_llist() // empty exit idxd_wq_thread() with no processing Add opportunistic descriptor completion in the abort path in order to remove the missed completion. Fixes: 6b4b87f2c31a ("dmaengine: idxd: fix submission race window") Reported-by: Ming Li <ming4.li@xxxxxxxxx> Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx> Link: https://lore.kernel.org/r/163898288714.443911.16084982766671976640.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/dma/idxd/submit.c b/drivers/dma/idxd/submit.c index de76fb4abac24..83452fbbb168b 100644 --- a/drivers/dma/idxd/submit.c +++ b/drivers/dma/idxd/submit.c @@ -106,6 +106,7 @@ static void llist_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie, { struct idxd_desc *d, *t, *found = NULL; struct llist_node *head; + LIST_HEAD(flist); desc->completion->status = IDXD_COMP_DESC_ABORT; /* @@ -120,7 +121,11 @@ static void llist_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie, found = desc; continue; } - list_add_tail(&desc->list, &ie->work_list); + + if (d->completion->status) + list_add_tail(&d->list, &flist); + else + list_add_tail(&d->list, &ie->work_list); } } @@ -130,6 +135,17 @@ static void llist_abort_desc(struct idxd_wq *wq, struct idxd_irq_entry *ie, if (found) complete_desc(found, IDXD_COMPLETE_ABORT); + + /* + * complete_desc() will return desc to allocator and the desc can be + * acquired by a different process and the desc->list can be modified. + * Delete desc from list so the list trasversing does not get corrupted + * by the other process. + */ + list_for_each_entry_safe(d, t, &flist, list) { + list_del_init(&d->list); + complete_desc(d, IDXD_COMPLETE_NORMAL); + } } int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc)