From: Xie Yongji <xieyongji@bytedance.com>
To: mst@redhat.com, jasowang@redhat.com, stefanha@redhat.com,
sgarzare@redhat.com, parav@nvidia.com, hch@infradead.org,
christian.brauner@canonical.com, rdunlap@infradead.org,
willy@infradead.org, viro@zeniv.linux.org.uk, axboe@kernel.dk,
bcrl@kvack.org, corbet@lwn.net, mika.penttila@nextfour.com,
dan.carpenter@oracle.com, joro@8bytes.org
Cc: virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, kvm@vger.kernel.org,
linux-fsdevel@vger.kernel.org, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v7 03/12] eventfd: Increase the recursion depth of eventfd_signal()
Date: Mon, 17 May 2021 17:55:04 +0800 [thread overview]
Message-ID: <20210517095513.850-4-xieyongji@bytedance.com> (raw)
In-Reply-To: <20210517095513.850-1-xieyongji@bytedance.com>
Increase the recursion depth of eventfd_signal() to 1. This
is the maximum recursion depth we have found so far, which
can be triggered with the following call chain:
kvm_io_bus_write [kvm]
--> ioeventfd_write [kvm]
--> eventfd_signal [eventfd]
--> vhost_poll_wakeup [vhost]
--> vduse_vdpa_kick_vq [vduse]
--> eventfd_signal [eventfd]
Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Acked-by: Jason Wang <jasowang@redhat.com>
---
fs/eventfd.c | 2 +-
include/linux/eventfd.h | 5 ++++-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/eventfd.c b/fs/eventfd.c
index e265b6dd4f34..cc7cd1dbedd3 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -71,7 +71,7 @@ __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
* it returns true, the eventfd_signal() call should be deferred to a
* safe context.
*/
- if (WARN_ON_ONCE(this_cpu_read(eventfd_wake_count)))
+ if (WARN_ON_ONCE(this_cpu_read(eventfd_wake_count) > EFD_WAKE_DEPTH))
return 0;
spin_lock_irqsave(&ctx->wqh.lock, flags);
diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
index fa0a524baed0..886d99cd38ef 100644
--- a/include/linux/eventfd.h
+++ b/include/linux/eventfd.h
@@ -29,6 +29,9 @@
#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
+/* Maximum recursion depth */
+#define EFD_WAKE_DEPTH 1
+
struct eventfd_ctx;
struct file;
@@ -47,7 +50,7 @@ DECLARE_PER_CPU(int, eventfd_wake_count);
static inline bool eventfd_signal_count(void)
{
- return this_cpu_read(eventfd_wake_count);
+ return this_cpu_read(eventfd_wake_count) > EFD_WAKE_DEPTH;
}
#else /* CONFIG_EVENTFD */
--
2.11.0
next prev parent reply other threads:[~2021-05-17 9:56 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-17 9:55 [PATCH v7 00/12] Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-05-17 9:55 ` [PATCH v7 01/12] iova: Export alloc_iova_fast() Xie Yongji
2021-05-26 2:36 ` Jason Wang
2021-05-26 2:43 ` Yongji Xie
2021-05-17 9:55 ` [PATCH v7 02/12] file: Export receive_fd() to modules Xie Yongji
2021-05-20 6:18 ` Al Viro
2021-05-20 6:32 ` Yongji Xie
2021-05-17 9:55 ` Xie Yongji [this message]
2021-05-17 9:55 ` [PATCH v7 04/12] virtio-blk: Add validation for block size in config space Xie Yongji
2021-05-19 13:39 ` Yongji Xie
2021-05-19 14:42 ` Dan Carpenter
2021-05-20 5:25 ` Yongji Xie
2021-05-20 5:43 ` Michael S. Tsirkin
2021-05-20 7:08 ` Yongji Xie
2021-05-17 9:55 ` [PATCH v7 05/12] virtio_scsi: Add validation for residual bytes from response Xie Yongji
2021-05-26 2:41 ` Jason Wang
2021-05-17 9:55 ` [PATCH v7 06/12] vhost-iotlb: Add an opaque pointer for vhost IOTLB Xie Yongji
2021-05-17 9:55 ` [PATCH v7 07/12] vdpa: Add an opaque pointer for vdpa_config_ops.dma_map() Xie Yongji
2021-05-17 9:55 ` [PATCH v7 08/12] vdpa: factor out vhost_vdpa_pa_map() and vhost_vdpa_pa_unmap() Xie Yongji
2021-05-17 9:55 ` [PATCH v7 09/12] vdpa: Support transferring virtual addressing during DMA mapping Xie Yongji
2021-05-17 9:55 ` [PATCH v7 10/12] vduse: Implement an MMU-based IOMMU driver Xie Yongji
2021-05-17 9:55 ` [PATCH v7 11/12] vduse: Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-05-20 6:28 ` Al Viro
2021-05-20 7:03 ` Yongji Xie
2021-05-27 4:12 ` Jason Wang
2021-05-27 4:57 ` Yongji Xie
2021-05-27 5:00 ` Jason Wang
2021-05-27 5:08 ` Yongji Xie
2021-05-27 5:40 ` Jason Wang
2021-05-27 7:34 ` Yongji Xie
2021-05-27 8:41 ` Jason Wang
2021-05-27 8:43 ` Jason Wang
2021-05-27 10:14 ` Yongji Xie
2021-05-28 1:33 ` Jason Wang
2021-05-28 3:54 ` Yongji Xie
2021-05-28 6:38 ` Jason Wang
2021-05-27 13:17 ` Yongji Xie
2021-05-28 2:31 ` Jason Wang
2021-05-31 4:27 ` Yongji Xie
2021-05-31 4:38 ` Jason Wang
2021-05-31 6:24 ` Yongji Xie
2021-05-31 4:56 ` Greg KH
2021-05-31 6:19 ` Yongji Xie
2021-05-31 6:32 ` Greg KH
2021-05-31 7:13 ` Yongji Xie
2021-05-17 9:55 ` [PATCH v7 12/12] Documentation: Add documentation for VDUSE Xie Yongji
2021-05-20 6:06 ` [PATCH v7 00/12] Introduce VDUSE - vDPA Device in Userspace Michael S. Tsirkin
2021-05-20 9:06 ` Yongji Xie
2021-05-25 6:40 ` Jason Wang
2021-05-25 6:48 ` Michael S. Tsirkin
2021-05-25 7:11 ` Jason Wang
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