This is a note to let you know that I've just added the patch titled
eventfd: provide a eventfd_signal_mask() helper
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
eventfd-provide-a-eventfd_signal_mask-helper.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 53270319f184c35499cf2ffeac8a75078b94934a Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Sun, 20 Nov 2022 10:13:44 -0700
Subject: eventfd: provide a eventfd_signal_mask() helper
From: Jens Axboe <axboe@xxxxxxxxx>
[ Upstream commit 03e02acda8e267a8183e1e0ed289ff1ef9cd7ed8 ]
This is identical to eventfd_signal(), but it allows the caller to pass
in a mask to be used for the poll wakeup key. The use case is avoiding
repeated multishot triggers if we have a dependency between eventfd and
io_uring.
If we setup an eventfd context and register that as the io_uring eventfd,
and at the same time queue a multishot poll request for the eventfd
context, then any CQE posted will repeatedly trigger the multishot request
until it terminates when the CQ ring overflows.
In preparation for io_uring detecting this circular dependency, add the
mentioned helper so that io_uring can pass in EPOLL_URING as part of the
poll wakeup key.
Cc: stable@xxxxxxxxxxxxxxx # 6.0
[axboe: fold in !CONFIG_EVENTFD fix from Zhang Qilong]
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/eventfd.c | 37 +++++++++++++++++++++----------------
include/linux/eventfd.h | 7 +++++++
2 files changed, 28 insertions(+), 16 deletions(-)
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -45,21 +45,7 @@ struct eventfd_ctx {
int id;
};
-/**
- * eventfd_signal - Adds @n to the eventfd counter.
- * @ctx: [in] Pointer to the eventfd context.
- * @n: [in] Value of the counter to be added to the eventfd internal counter.
- * The value cannot be negative.
- *
- * This function is supposed to be called by the kernel in paths that do not
- * allow sleeping. In this function we allow the counter to reach the ULLONG_MAX
- * value, and we signal this as overflow condition by returning a EPOLLERR
- * to poll(2).
- *
- * Returns the amount by which the counter was incremented. This will be less
- * than @n if the counter has overflowed.
- */
-__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
+__u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n, unsigned mask)
{
unsigned long flags;
@@ -80,12 +66,31 @@ __u64 eventfd_signal(struct eventfd_ctx
n = ULLONG_MAX - ctx->count;
ctx->count += n;
if (waitqueue_active(&ctx->wqh))
- wake_up_locked_poll(&ctx->wqh, EPOLLIN);
+ wake_up_locked_poll(&ctx->wqh, EPOLLIN | mask);
this_cpu_dec(eventfd_wake_count);
spin_unlock_irqrestore(&ctx->wqh.lock, flags);
return n;
}
+
+/**
+ * eventfd_signal - Adds @n to the eventfd counter.
+ * @ctx: [in] Pointer to the eventfd context.
+ * @n: [in] Value of the counter to be added to the eventfd internal counter.
+ * The value cannot be negative.
+ *
+ * This function is supposed to be called by the kernel in paths that do not
+ * allow sleeping. In this function we allow the counter to reach the ULLONG_MAX
+ * value, and we signal this as overflow condition by returning a EPOLLERR
+ * to poll(2).
+ *
+ * Returns the amount by which the counter was incremented. This will be less
+ * than @n if the counter has overflowed.
+ */
+__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
+{
+ return eventfd_signal_mask(ctx, n, 0);
+}
EXPORT_SYMBOL_GPL(eventfd_signal);
static void eventfd_free_ctx(struct eventfd_ctx *ctx)
--- a/include/linux/eventfd.h
+++ b/include/linux/eventfd.h
@@ -39,6 +39,7 @@ struct file *eventfd_fget(int fd);
struct eventfd_ctx *eventfd_ctx_fdget(int fd);
struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
__u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
+__u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n, unsigned mask);
int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
__u64 *cnt);
@@ -65,6 +66,12 @@ static inline int eventfd_signal(struct
{
return -ENOSYS;
}
+
+static inline int eventfd_signal_mask(struct eventfd_ctx *ctx, __u64 n,
+ unsigned mask)
+{
+ return -ENOSYS;
+}
static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
{
Patches currently in stable-queue which might be from axboe@xxxxxxxxx are
queue-5.10/x86-process-setup-io_threads-more-like-normal-user-space-threads.patch
queue-5.10/powerpc-add-support-for-tif_notify_signal.patch
queue-5.10/eventfd-provide-a-eventfd_signal_mask-helper.patch
queue-5.10/fs-provide-locked-helper-variant-of-close_fd_get_file.patch
queue-5.10/relay-fix-type-mismatch-when-allocating-memory-in-re.patch
queue-5.10/eventfd-change-int-to-__u64-in-eventfd_signal-ifndef.patch
queue-5.10/io_uring-pass-in-epoll_uring_wake-for-eventfd-signaling-and-wakeups.patch
queue-5.10/blk-mq-fix-possible-memleak-when-register-hctx-faile.patch
queue-5.10/fix-handling-of-nd-depth-on-lookup_cached-failures-in-try_to_unlazy.patch
queue-5.10/net-provide-__sys_shutdown_sock-that-takes-a-socket.patch
queue-5.10/task_work-unconditionally-run-task_work-from-get_signal.patch
queue-5.10/openrisc-add-support-for-tif_notify_signal.patch
queue-5.10/signal-add-task_sigpending-helper.patch
queue-5.10/net-remove-cmsg-restriction-from-io_uring-based-send-recvmsg-calls.patch
queue-5.10/alpha-add-support-for-tif_notify_signal.patch
queue-5.10/nios32-add-support-for-tif_notify_signal.patch
queue-5.10/ia64-don-t-call-handle_signal-unless-there-s-actually-a-signal-queued.patch
queue-5.10/task_work-remove-legacy-twa_signal-path.patch
queue-5.10/revert-proc-don-t-allow-async-path-resolution-of-proc-self-components.patch
queue-5.10/m68k-add-support-for-tif_notify_signal.patch
queue-5.10/s390-add-support-for-tif_notify_signal.patch
queue-5.10/um-add-support-for-tif_notify_signal.patch
queue-5.10/tools-headers-uapi-sync-openat2.h-with-the-kernel-sources.patch
queue-5.10/kernel-provide-create_io_thread-helper.patch
queue-5.10/iov_iter-add-helper-to-save-iov_iter-state.patch
queue-5.10/arc-unbork-5.11-bootup-fix-snafu-in-_tif_notify_signal-handling.patch
queue-5.10/arch-ensure-parisc-powerpc-handle-pf_io_worker-in-copy_thread.patch
queue-5.10/csky-add-support-for-tif_notify_signal.patch
queue-5.10/arm-add-support-for-tif_notify_signal.patch
queue-5.10/kernel-stop-masking-signals-in-create_io_thread.patch
queue-5.10/fs-expose-lookup_cached-through-openat2-resolve_cached.patch
queue-5.10/task_work-add-helper-for-more-targeted-task_work-canceling.patch
queue-5.10/nds32-add-support-for-tif_notify_signal.patch
queue-5.10/signal-kill-jobctl_task_work.patch
queue-5.10/hexagon-add-support-for-tif_notify_signal.patch
queue-5.10/sh-add-support-for-tif_notify_signal.patch
queue-5.10/riscv-add-support-for-tif_notify_signal.patch
queue-5.10/h8300-add-support-for-tif_notify_signal.patch
queue-5.10/io_uring-import-5.15-stable-io_uring.patch
queue-5.10/sparc-add-support-for-tif_notify_signal.patch
queue-5.10/blktrace-fix-output-non-blktrace-event-when-blk_clas.patch
queue-5.10/eventpoll-add-epoll_uring_wake-poll-wakeup-flag.patch
queue-5.10/parisc-add-support-for-tif_notify_signal.patch
queue-5.10/entry-add-support-for-tif_notify_signal.patch
queue-5.10/x86-wire-up-tif_notify_signal.patch
queue-5.10/task_work-use-tif_notify_signal-if-available.patch
queue-5.10/drbd-fix-an-invalid-memory-access-caused-by-incorrec.patch
queue-5.10/kernel-don-t-call-do_exit-for-pf_io_worker-threads.patch
queue-5.10/kernel-allow-fork-with-tif_notify_signal-pending.patch
queue-5.10/pata_ipx4xx_cf-fix-unsigned-comparison-with-less-tha.patch
queue-5.10/mips-add-support-for-tif_notify_signal.patch
queue-5.10/xtensa-add-support-for-tif_notify_signal.patch
queue-5.10/c6x-add-support-for-tif_notify_signal.patch
queue-5.10/microblaze-add-support-for-tif_notify_signal.patch
queue-5.10/net-add-accept-helper-not-installing-fd.patch
queue-5.10/ia64-add-support-for-tif_notify_signal.patch
queue-5.10/arm64-add-support-for-tif_notify_signal.patch
queue-5.10/arc-add-support-for-tif_notify_signal.patch
queue-5.10/revert-proc-don-t-allow-async-path-resolution-of-proc-thread-self-components.patch
queue-5.10/fs-make-do_renameat2-take-struct-filename.patch
queue-5.10/kernel-remove-checking-for-tif_notify_signal.patch
queue-5.10/arch-setup-pf_io_worker-threads-like-pf_kthread.patch
queue-5.10/nvme-pci-fix-mempool-alloc-size.patch
queue-5.10/fs-add-support-for-lookup_cached.patch
