Messages in this thread Patch in this message |  | | From | Nadav Amit <> | Subject | [RFC PATCH 04/13] fs/userfaultfd: simplify locks in userfaultfd_ctx_read | Date | Sat, 28 Nov 2020 16:45:39 -0800 |
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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
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