From: Christoph Hellwig <hch@lst.de>
To: viro@zeniv.linux.org.uk
Cc: Avi Kivity <avi@scylladb.com>,
linux-aio@kvack.org, linux-fsdevel@vger.kernel.org,
netdev@vger.kernel.org, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 07/36] aio: add delayed cancel support
Date: Mon, 22 Jan 2018 21:12:14 +0100 [thread overview]
Message-ID: <20180122201243.31610-8-hch@lst.de> (raw)
In-Reply-To: <20180122201243.31610-1-hch@lst.de>
The upcoming aio poll support would like to be able to complete the
iocb inline from the cancellation context, but that would cause
a lock order reversal. Add support for optionally moving the cancelation
outside the context lock to avoid this reversal.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
---
fs/aio.c | 49 ++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 38 insertions(+), 11 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 0b6394b4e528..9d7d6e4cde87 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -170,6 +170,10 @@ struct aio_kiocb {
struct list_head ki_list; /* the aio core uses this
* for cancellation */
+ unsigned int flags; /* protected by ctx->ctx_lock */
+#define AIO_IOCB_DELAYED_CANCEL (1 << 0)
+#define AIO_IOCB_CANCELLED (1 << 1)
+
/*
* If the aio_resfd field of the userspace iocb is not zero,
* this is the underlying eventfd context to deliver events to.
@@ -536,9 +540,9 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
#define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
#define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
-void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
+static void __kiocb_set_cancel_fn(struct aio_kiocb *req,
+ kiocb_cancel_fn *cancel, unsigned int iocb_flags)
{
- struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw);
struct kioctx *ctx = req->ki_ctx;
unsigned long flags;
@@ -548,8 +552,15 @@ void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
spin_lock_irqsave(&ctx->ctx_lock, flags);
list_add_tail(&req->ki_list, &ctx->active_reqs);
req->ki_cancel = cancel;
+ req->flags |= iocb_flags;
spin_unlock_irqrestore(&ctx->ctx_lock, flags);
}
+
+void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
+{
+ return __kiocb_set_cancel_fn(container_of(iocb, struct aio_kiocb, rw),
+ cancel, 0);
+}
EXPORT_SYMBOL(kiocb_set_cancel_fn);
/*
@@ -603,17 +614,27 @@ static void free_ioctx_users(struct percpu_ref *ref)
{
struct kioctx *ctx = container_of(ref, struct kioctx, users);
struct aio_kiocb *req;
+ LIST_HEAD(list);
spin_lock_irq(&ctx->ctx_lock);
-
while (!list_empty(&ctx->active_reqs)) {
req = list_first_entry(&ctx->active_reqs,
struct aio_kiocb, ki_list);
- kiocb_cancel(req);
- }
+ if (req->flags & AIO_IOCB_DELAYED_CANCEL) {
+ req->flags |= AIO_IOCB_CANCELLED;
+ list_move_tail(&req->ki_list, &list);
+ } else {
+ kiocb_cancel(req);
+ }
+ }
spin_unlock_irq(&ctx->ctx_lock);
+ while (!list_empty(&list)) {
+ req = list_first_entry(&list, struct aio_kiocb, ki_list);
+ kiocb_cancel(req);
+ }
+
percpu_ref_kill(&ctx->reqs);
percpu_ref_put(&ctx->reqs);
}
@@ -1785,15 +1806,22 @@ SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
if (unlikely(!ctx))
return -EINVAL;
- spin_lock_irq(&ctx->ctx_lock);
+ ret = -EINVAL;
+ spin_lock_irq(&ctx->ctx_lock);
kiocb = lookup_kiocb(ctx, iocb, key);
+ if (kiocb) {
+ if (kiocb->flags & AIO_IOCB_DELAYED_CANCEL) {
+ kiocb->flags |= AIO_IOCB_CANCELLED;
+ } else {
+ ret = kiocb_cancel(kiocb);
+ kiocb = NULL;
+ }
+ }
+ spin_unlock_irq(&ctx->ctx_lock);
+
if (kiocb)
ret = kiocb_cancel(kiocb);
- else
- ret = -EINVAL;
-
- spin_unlock_irq(&ctx->ctx_lock);
if (!ret) {
/*
@@ -1805,7 +1833,6 @@ SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
}
percpu_ref_put(&ctx->users);
-
return ret;
}
--
2.14.2
--
To unsubscribe, send a message with 'unsubscribe linux-aio' in
the body to majordomo@kvack.org. For more info on Linux AIO,
see: http://www.kvack.org/aio/
Don't email: <a href=mailto:"aart@kvack.org">aart@kvack.org</a>
next prev parent reply other threads:[~2018-01-22 20:12 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-22 20:12 aio poll, io_pgetevents and a new in-kernel poll API V4 Christoph Hellwig
[not found] ` <20180122201243.31610-1-hch-jcswGhMUV9g@public.gmane.org>
2018-01-22 20:12 ` [PATCH 01/36] aio: don't print the page size at boot time Christoph Hellwig
2018-01-22 20:12 ` [PATCH 25/36] net/sctp: convert to ->poll_mask Christoph Hellwig
2018-01-22 20:12 ` [PATCH 02/36] aio: remove an outdated comment in aio_complete Christoph Hellwig
2018-01-22 20:12 ` [PATCH 03/36] aio: refactor read/write iocb setup Christoph Hellwig
2018-01-22 20:12 ` [PATCH 04/36] aio: sanitize ki_list handling Christoph Hellwig
2018-01-22 20:12 ` [PATCH 05/36] aio: simplify cancellation Christoph Hellwig
2018-01-22 20:12 ` [PATCH 06/36] aio: delete iocbs from the active_reqs list in kiocb_cancel Christoph Hellwig
2018-01-22 20:12 ` Christoph Hellwig [this message]
2018-01-22 20:12 ` [PATCH 08/36] aio: implement io_pgetevents Christoph Hellwig
2018-01-24 19:24 ` Jeff Moyer
2018-01-22 20:12 ` [PATCH 09/36] fs: unexport poll_schedule_timeout Christoph Hellwig
2018-01-22 20:12 ` [PATCH 10/36] fs: cleanup do_pollfd Christoph Hellwig
2018-01-22 20:12 ` [PATCH 11/36] fs: update documentation for __poll_t Christoph Hellwig
2018-01-22 20:12 ` [PATCH 12/36] fs: add new vfs_poll and file_can_poll helpers Christoph Hellwig
2018-01-22 20:12 ` [PATCH 13/36] fs: introduce new ->get_poll_head and ->poll_mask methods Christoph Hellwig
2018-01-22 20:12 ` [PATCH 14/36] aio: implement IOCB_CMD_POLL Christoph Hellwig
2018-01-24 19:24 ` Jeff Moyer
2018-01-22 20:12 ` [PATCH 15/36] net: refactor socket_poll Christoph Hellwig
2018-01-22 20:12 ` [PATCH 16/36] net: add support for ->poll_mask in proto_ops Christoph Hellwig
2018-01-22 20:12 ` [PATCH 17/36] net: remove sock_no_poll Christoph Hellwig
2018-01-22 20:12 ` [PATCH 18/36] net/tcp: convert to ->poll_mask Christoph Hellwig
2018-01-22 20:12 ` [PATCH 19/36] net/unix: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 20/36] net: convert datagram_poll users tp ->poll_mask Christoph Hellwig
2018-01-22 20:12 ` [PATCH 21/36] net/dccp: convert to ->poll_mask Christoph Hellwig
2018-01-22 20:12 ` [PATCH 22/36] net/atm: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 23/36] net/vmw_vsock: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 24/36] net/tipc: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 26/36] net/bluetooth: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 27/36] net/caif: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 28/36] net/nfc: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 29/36] net/phonet: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 30/36] net/iucv: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 31/36] net/rxrpc: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 32/36] crypto: af_alg: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 33/36] pipe: " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 34/36] eventfd: switch " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 35/36] timerfd: convert " Christoph Hellwig
2018-01-22 20:12 ` [PATCH 36/36] random: " Christoph Hellwig
2018-01-25 20:10 ` aio poll, io_pgetevents and a new in-kernel poll API V4 Benjamin LaHaise
2018-01-26 12:31 ` Christoph Hellwig
-- strict thread matches above, loose matches on Subject: below --
2018-03-05 21:27 aio poll, io_pgetevents and a new in-kernel poll API V5 Christoph Hellwig
2018-03-05 21:27 ` [PATCH 07/36] aio: add delayed cancel support Christoph Hellwig
2018-03-20 3:19 ` Darrick J. Wong
2018-03-20 15:20 ` Christoph Hellwig
2018-01-17 19:27 aio poll, io_pgetevents and a new in-kernel poll API V3 Christoph Hellwig
2018-01-17 19:27 ` [PATCH 07/36] aio: add delayed cancel support Christoph Hellwig
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180122201243.31610-8-hch@lst.de \
--to=hch@lst.de \
--cc=avi@scylladb.com \
--cc=linux-aio@kvack.org \
--cc=linux-api@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).