From: Xie Yongji <xieyongji@bytedance.com>
To: mst@redhat.com, jasowang@redhat.com, stefanha@redhat.com,
sgarzare@redhat.com, parav@nvidia.com, bob.liu@oracle.com,
hch@infradead.org, 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
Cc: virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, kvm@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: [PATCH v5 02/11] eventfd: Increase the recursion depth of eventfd_signal()
Date: Mon, 15 Mar 2021 13:37:12 +0800 [thread overview]
Message-ID: <20210315053721.189-3-xieyongji@bytedance.com> (raw)
In-Reply-To: <20210315053721.189-1-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]
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Xie Yongji <xieyongji@bytedance.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:[~2021-03-15 5:38 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 5:37 [PATCH v5 00/11] Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-03-15 5:37 ` [PATCH v5 01/11] file: Export __receive_fd() to modules Xie Yongji
2021-03-15 9:08 ` Christoph Hellwig
2021-03-15 9:46 ` Yongji Xie
2021-03-15 14:44 ` Christian Brauner
2021-03-16 2:48 ` Yongji Xie
2021-03-25 8:23 ` Christoph Hellwig
2021-03-25 11:04 ` Yongji Xie
2021-03-15 5:37 ` Xie Yongji [this message]
2021-03-15 5:37 ` [PATCH v5 03/11] vhost-vdpa: protect concurrent access to vhost device iotlb Xie Yongji
2021-03-23 3:02 ` Jason Wang
2021-03-23 7:25 ` Yongji Xie
2021-03-25 11:08 ` Stefano Garzarella
2021-03-15 5:37 ` [PATCH v5 04/11] vhost-iotlb: Add an opaque pointer for vhost IOTLB Xie Yongji
2021-03-15 5:37 ` [PATCH v5 05/11] vdpa: Add an opaque pointer for vdpa_config_ops.dma_map() Xie Yongji
2021-03-15 5:37 ` [PATCH v5 06/11] vdpa: factor out vhost_vdpa_pa_map() Xie Yongji
2021-03-23 3:09 ` Jason Wang
2021-03-15 5:37 ` [PATCH v5 07/11] vdpa: Support transferring virtual addressing during DMA mapping Xie Yongji
2021-03-23 3:13 ` Jason Wang
2021-03-23 7:26 ` Yongji Xie
2021-03-15 5:37 ` [PATCH v5 08/11] vduse: Implement an MMU-based IOMMU driver Xie Yongji
2021-03-24 3:54 ` Jason Wang
2021-03-24 7:39 ` Yongji Xie
2021-03-25 4:52 ` Jason Wang
2021-03-25 7:38 ` Yongji Xie
2021-03-26 4:26 ` Jason Wang
2021-03-26 5:14 ` Yongji Xie
[not found] ` <75e3b941-dfd2-ebbc-d752-8f25c1f14cab@redhat.com>
2021-03-26 6:56 ` Yongji Xie
2021-03-26 7:36 ` Jason Wang
2021-03-15 5:37 ` [PATCH v5 09/11] vduse: Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-03-24 4:43 ` Jason Wang
2021-03-24 8:55 ` Yongji Xie
2021-03-25 6:30 ` Jason Wang
2021-03-25 7:47 ` Yongji Xie
2021-03-15 5:37 ` [PATCH v5 10/11] vduse: Add config interrupt support Xie Yongji
2021-03-24 4:45 ` Jason Wang
2021-03-24 8:56 ` Yongji Xie
2021-03-15 5:37 ` [PATCH v5 11/11] Documentation: Add documentation for VDUSE Xie Yongji
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