From: Nadav Amit <nadav.amit@gmail.com>
To: linux-fsdevel@vger.kernel.org
Cc: Nadav Amit <namit@vmware.com>, Jens Axboe <axboe@kernel.dk>,
Andrea Arcangeli <aarcange@redhat.com>,
Peter Xu <peterx@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
io-uring@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: [RFC PATCH 04/13] fs/userfaultfd: simplify locks in userfaultfd_ctx_read
Date: Sat, 28 Nov 2020 16:45:39 -0800 [thread overview]
Message-ID: <20201129004548.1619714-5-namit@vmware.com> (raw)
In-Reply-To: <20201129004548.1619714-1-namit@vmware.com>
From: Nadav Amit <namit@vmware.com>
Small refactoring to reduce the number of locations in which locks are
released in userfaultfd_ctx_read(), as this makes the understanding of
the code and its changes harder.
No functional change intended.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: io-uring@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Nadav Amit <namit@vmware.com>
---
fs/userfaultfd.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 4fe07c1a44c6..fedf7c1615d5 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1039,6 +1039,7 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
set_current_state(TASK_INTERRUPTIBLE);
spin_lock(&ctx->fault_pending_wqh.lock);
uwq = find_userfault(ctx);
+ ret = -EAGAIN;
if (uwq) {
/*
* Use a seqcount to repeat the lockless check
@@ -1077,11 +1078,11 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
/* careful to always initialize msg if ret == 0 */
*msg = uwq->msg;
- spin_unlock(&ctx->fault_pending_wqh.lock);
ret = 0;
- break;
}
spin_unlock(&ctx->fault_pending_wqh.lock);
+ if (!ret)
+ break;
spin_lock(&ctx->event_wqh.lock);
uwq = find_userfault_evt(ctx);
@@ -1099,17 +1100,14 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
* reference on it.
*/
userfaultfd_ctx_get(fork_nctx);
- spin_unlock(&ctx->event_wqh.lock);
- ret = 0;
- break;
+ } else {
+ userfaultfd_event_complete(ctx, uwq);
}
-
- userfaultfd_event_complete(ctx, uwq);
- spin_unlock(&ctx->event_wqh.lock);
ret = 0;
- break;
}
spin_unlock(&ctx->event_wqh.lock);
+ if (!ret)
+ break;
if (signal_pending(current)) {
ret = -ERESTARTSYS;
--
2.25.1
next prev parent reply other threads:[~2020-11-29 0:50 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-29 0:45 [RFC PATCH 00/13] fs/userfaultfd: support iouring and polling Nadav Amit
2020-11-29 0:45 ` [RFC PATCH 01/13] fs/userfaultfd: fix wrong error code on WP & !VM_MAYWRITE Nadav Amit
2020-12-01 21:22 ` Mike Kravetz
2020-12-21 19:01 ` Peter Xu
2020-11-29 0:45 ` [RFC PATCH 02/13] fs/userfaultfd: fix wrong file usage with iouring Nadav Amit
2020-11-29 0:45 ` [RFC PATCH 03/13] selftests/vm/userfaultfd: wake after copy failure Nadav Amit
2020-12-21 19:28 ` Peter Xu
2020-12-21 19:51 ` Nadav Amit
2020-12-21 20:52 ` Peter Xu
2020-12-21 20:54 ` Nadav Amit
2020-11-29 0:45 ` Nadav Amit [this message]
2020-11-29 0:45 ` [RFC PATCH 05/13] fs/userfaultfd: introduce UFFD_FEATURE_POLL Nadav Amit
2020-11-29 0:45 ` [RFC PATCH 06/13] iov_iter: support atomic copy_page_from_iter_iovec() Nadav Amit
2020-11-29 0:45 ` [RFC PATCH 07/13] fs/userfaultfd: support read_iter to use io_uring Nadav Amit
2020-11-30 18:20 ` Jens Axboe
2020-11-30 19:23 ` Nadav Amit
2020-11-29 0:45 ` [RFC PATCH 08/13] fs/userfaultfd: complete reads asynchronously Nadav Amit
2020-11-29 0:45 ` [RFC PATCH 09/13] fs/userfaultfd: use iov_iter for copy/zero Nadav Amit
2020-11-29 0:45 ` [RFC PATCH 10/13] fs/userfaultfd: add write_iter() interface Nadav Amit
2020-11-29 0:45 ` [RFC PATCH 11/13] fs/userfaultfd: complete write asynchronously Nadav Amit
2020-12-02 7:12 ` Nadav Amit
2020-11-29 0:45 ` [RFC PATCH 12/13] fs/userfaultfd: kmem-cache for wait-queue objects Nadav Amit
2020-11-30 19:51 ` Nadav Amit
2020-12-03 5:19 ` [fs/userfaultfd] fec9227821: will-it-scale.per_process_ops -5.5% regression kernel test robot
2020-11-29 0:45 ` [RFC PATCH 13/13] selftests/vm/userfaultfd: iouring and polling tests Nadav Amit
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