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dmaengine: idxd: fix missed completion on abort path

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[ Upstream commit 8affd8a4b5 ]

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: 6b4b87f2c3 ("dmaengine: idxd: fix submission race window")
Reported-by: Ming Li <ming4.li@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/163898288714.443911.16084982766671976640.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Dave Jiang 2021-12-08 10:01:27 -07:00 committed by Greg Kroah-Hartman
parent 088e4d7dba
commit ee3701c4d9
1 changed files with 17 additions and 1 deletions
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18
drivers/dma/idxd/submit.c
View file

@ -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)