[Bug libc/24963] deadlock between freopen and fclose

["yisheng dot xys at alibaba-inc dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=24963

--- Comment #2 from Yisheng Xie <yisheng.xys@alibaba-inc.com> ---
(In reply to Carlos O'Donell from comment #1)
> This looks like it real problem.
> 
> The bug is likely in _IO_new_fclose.
> 
> We should lock fp first, and then with fp acquired lock the whole list.
> 
> All threads will try to operate on fp first, wait, and then attempt any more
> complex operations on fp next.
> 
> e.g.
> 
> diff --git a/libio/iofclose.c b/libio/iofclose.c
> index 8a80dd0b78..a7c5357944 100644
> --- a/libio/iofclose.c
> +++ b/libio/iofclose.c
> @@ -44,11 +44,12 @@ _IO_new_fclose (FILE *fp)
>      return _IO_old_fclose (fp);
>  #endif
>  
> +  _IO_acquire_lock (fp);
> +
>    /* First unlink the stream.  */
>    if (fp->_flags & _IO_IS_FILEBUF)
>      _IO_un_link ((struct _IO_FILE_plus *) fp);
>  
> -  _IO_acquire_lock (fp);
>    if (fp->_flags & _IO_IS_FILEBUF)
>      status = _IO_file_close_it (fp);
>    else
> ---
> 
> Someone needs to test and review a solution to this problem.
> 
> Yisheng are you working on a solution to post to libc-alpha?

Yeah, get it. I think it should be the solution to resolve the problem I met.

Can you send a patch to libc mail-list.

-- 
You are receiving this mail because:
You are on the CC list for the bug.