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bdev: defer completions from within submit_request

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If a blockdev module calls spdk_bdev_io_complete() within its
submit_request function, and the user's completion callback issues a new
I/O, it is possible to cause infinite recursion, consuming all available
stack space.

To avoid this, track whether a bdev_io is being processed by
submit_request, and if io_complete() is called in this case, defer the
completion via an event.

Change-Id: I6ccdb8ed4ee0d5738e6c9840d35431de52bd5fa2
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
This commit is contained in:
Daniel Verkamp 2017-01-12 10:58:20 -07:00 committed by Jim Harris
parent 360a3da3d7
commit 2138676573
2 changed files with 34 additions and 0 deletions
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8
include/spdk/bdev.h
View File

@ -265,6 +265,14 @@ struct spdk_bdev_io {
/** Status for the IO */ /** Status for the IO */
enum spdk_bdev_io_status status; enum spdk_bdev_io_status status;
/**
* Set to true while the bdev module submit_request function is in progress.
*
* This is used to decide whether spdk_bdev_io_complete() can complete the I/O directly
* or if completion must be deferred via an event.
*/
bool in_submit_request;
/** Used in virtual device (e.g., RAID), indicates its parent spdk_bdev_io **/ /** Used in virtual device (e.g., RAID), indicates its parent spdk_bdev_io **/
struct spdk_bdev_io *parent; struct spdk_bdev_io *parent;

26
lib/bdev/bdev.c
View File

@ -415,7 +415,9 @@ __submit_request(struct spdk_bdev *bdev, struct spdk_bdev_io *bdev_io)
if (bdev_io->type == SPDK_BDEV_IO_TYPE_RESET) { if (bdev_io->type == SPDK_BDEV_IO_TYPE_RESET) {
spdk_bdev_cleanup_pending_rbuf_io(bdev); spdk_bdev_cleanup_pending_rbuf_io(bdev);
} }
bdev_io->in_submit_request = true;
bdev->fn_table->submit_request(bdev_io); bdev->fn_table->submit_request(bdev_io);
bdev_io->in_submit_request = false;
} }
static int static int
@ -438,6 +440,7 @@ spdk_bdev_io_init(struct spdk_bdev_io *bdev_io,
bdev_io->cb = cb; bdev_io->cb = cb;
bdev_io->gencnt = bdev->gencnt; bdev_io->gencnt = bdev->gencnt;
bdev_io->status = SPDK_BDEV_IO_STATUS_PENDING; bdev_io->status = SPDK_BDEV_IO_STATUS_PENDING;
bdev_io->in_submit_request = false;
TAILQ_INIT(&bdev_io->child_io); TAILQ_INIT(&bdev_io->child_io);
} }
@ -798,9 +801,32 @@ spdk_bdev_free_io(struct spdk_bdev_io *bdev_io)
return 0; return 0;
} }
static void
bdev_io_deferred_completion(void *arg1, void *arg2)
{
struct spdk_bdev_io *bdev_io = arg1;
enum spdk_bdev_io_status status = (enum spdk_bdev_io_status)arg2;
assert(bdev_io->in_submit_request == false);
spdk_bdev_io_complete(bdev_io, status);
}
void void
spdk_bdev_io_complete(struct spdk_bdev_io *bdev_io, enum spdk_bdev_io_status status) spdk_bdev_io_complete(struct spdk_bdev_io *bdev_io, enum spdk_bdev_io_status status)
{ {
if (bdev_io->in_submit_request) {
/*
* Defer completion via an event to avoid potential infinite recursion if the
* user's completion callback issues a new I/O.
*/
spdk_event_call(spdk_event_allocate(spdk_app_get_current_core(),
bdev_io_deferred_completion,
bdev_io,
(void *)status));
return;
}
if (bdev_io->type == SPDK_BDEV_IO_TYPE_RESET) { if (bdev_io->type == SPDK_BDEV_IO_TYPE_RESET) {
/* Successful reset */ /* Successful reset */
if (status == SPDK_BDEV_IO_STATUS_SUCCESS) { if (status == SPDK_BDEV_IO_STATUS_SUCCESS) {