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From: Jason Wang <jasowang@redhat.com>
To: Xie Yongji <xieyongji@bytedance.com>,
	mst@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,
	gregkh@linuxfoundation.org, zhe.he@windriver.com,
	xiaodong.liu@intel.com, joe@perches.com, robin.murphy@arm.com,
	will@kernel.org, john.garry@huawei.com
Cc: songmuchun@bytedance.com,
	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: Re: [PATCH v13 02/13] eventfd: Export eventfd_wake_count to modules
Date: Wed, 1 Sep 2021 10:50:40 +0800	[thread overview]
Message-ID: <0e486c0a-0055-e698-ffd2-31c4b75dae5d@redhat.com> (raw)
In-Reply-To: <20210831103634.33-3-xieyongji@bytedance.com>


在 2021/8/31 下午6:36, Xie Yongji 写道:
> Export eventfd_wake_count so that some modules can use
> the eventfd_signal_count() to check whether the
> eventfd_signal() call should be deferred to a safe context.
>
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>


And this matches the comment inside eventfd_signal():

         /*
          * Deadlock or stack overflow issues can happen if we recurse here
          * through waitqueue wakeup handlers. If the caller users 
potentially
          * nested waitqueues with custom wakeup handlers, then it should
          * check eventfd_signal_count() before calling this function. If
          * it returns true, the eventfd_signal() call should be 
deferred to a
          * safe context.
          */


So:

Acked-by: Jason Wang <jasowang@redhat.com>


> ---
>   fs/eventfd.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/fs/eventfd.c b/fs/eventfd.c
> index e265b6dd4f34..1b3130b8d6c1 100644
> --- a/fs/eventfd.c
> +++ b/fs/eventfd.c
> @@ -26,6 +26,7 @@
>   #include <linux/uio.h>
>   
>   DEFINE_PER_CPU(int, eventfd_wake_count);
> +EXPORT_PER_CPU_SYMBOL_GPL(eventfd_wake_count);
>   
>   static DEFINE_IDA(eventfd_ida);
>   


  reply	other threads:[~2021-09-01  2:52 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-31 10:36 [PATCH v13 00/13] Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-08-31 10:36 ` [PATCH v13 01/13] iova: Export alloc_iova_fast() and free_iova_fast() Xie Yongji
2021-08-31 10:36 ` [PATCH v13 02/13] eventfd: Export eventfd_wake_count to modules Xie Yongji
2021-09-01  2:50   ` Jason Wang [this message]
2021-08-31 10:36 ` [PATCH v13 03/13] file: Export receive_fd() " Xie Yongji
2021-09-05 15:57   ` Michael S. Tsirkin
2021-09-05 16:44     ` Al Viro
2021-08-31 10:36 ` [PATCH v13 04/13] vdpa: Fix some coding style issues Xie Yongji
2021-08-31 10:36 ` [PATCH v13 05/13] vdpa: Add reset callback in vdpa_config_ops Xie Yongji
2021-09-06  5:55   ` Michael S. Tsirkin
2021-09-06  6:09     ` Yongji Xie
2021-09-06  6:37       ` Michael S. Tsirkin
2021-09-06  7:06         ` Yongji Xie
2021-09-06  8:00           ` Michael S. Tsirkin
2021-09-06  8:45             ` Yongji Xie
2021-09-06 10:43               ` Michael S. Tsirkin
2021-09-06 12:13                 ` Yongji Xie
2021-08-31 10:36 ` [PATCH v13 06/13] vhost-vdpa: Handle the failure of vdpa_reset() Xie Yongji
2021-08-31 10:36 ` [PATCH v13 07/13] vhost-iotlb: Add an opaque pointer for vhost IOTLB Xie Yongji
2021-08-31 10:36 ` [PATCH v13 08/13] vdpa: Add an opaque pointer for vdpa_config_ops.dma_map() Xie Yongji
2021-08-31 10:36 ` [PATCH v13 09/13] vdpa: factor out vhost_vdpa_pa_map() and vhost_vdpa_pa_unmap() Xie Yongji
2021-08-31 10:36 ` [PATCH v13 10/13] vdpa: Support transferring virtual addressing during DMA mapping Xie Yongji
2021-08-31 10:36 ` [PATCH v13 11/13] vduse: Implement an MMU-based software IOTLB Xie Yongji
2021-08-31 10:36 ` [PATCH v13 12/13] vduse: Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-08-31 10:36 ` [PATCH v13 13/13] Documentation: Add documentation for VDUSE Xie Yongji
2021-10-11  7:32 ` [PATCH v13 00/13] Introduce VDUSE - vDPA Device in Userspace Liuxiangdong
2021-10-11  8:31   ` Yongji Xie
2021-10-11  8:32     ` Yongji Xie

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