Re: [Qemu-devel] [PATCH 3/4] 9p: add locking to V9fsDir

[Eric Blake <eblake@redhat.com>]

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On 06/02/2016 02:52 AM, Greg Kurz wrote:
> If several threads call concurrently readdir() with the same directory

s/call concurrently/concurrently call/

> stream pointer, it is possible that they all get a pointer to the same
> dirent structure, whose content is overwritten each time readdir() is
> called.
> 
> We must thus serialize accesses to the dirent structure.
> 
> This may be achieved with a mutex like below:
> 
> lock_mutex();
> 
> readdir();
> 
> // work with the dirent
> 
> unlock_mutex();
> 
> This patch adds all the locking, to prepare the switch to readdir().
> 
> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
> ---
>  hw/9pfs/9p.c |   21 +++++++++++++++++++++
>  hw/9pfs/9p.h |   16 ++++++++++++++++
>  2 files changed, 37 insertions(+)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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