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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Mateusz Guzik <mguzik@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Yann Droneaud <ydroneaud@opteya.com>,
	Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] fs: use a sequence counter instead of file_lock in fd_install
Date: Thu, 16 Apr 2015 19:09:32 +0100	[thread overview]
Message-ID: <20150416180932.GW889@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20150416121628.GA20615@mguzik>

On Thu, Apr 16, 2015 at 02:16:31PM +0200, Mateusz Guzik wrote:
> @@ -165,8 +165,10 @@ static int expand_fdtable(struct files_struct *files, int nr)
>  	cur_fdt = files_fdtable(files);
>  	if (nr >= cur_fdt->max_fds) {
>  		/* Continue as planned */
> +		write_seqcount_begin(&files->fdt_seqcount);
>  		copy_fdtable(new_fdt, cur_fdt);
>  		rcu_assign_pointer(files->fdt, new_fdt);
> +		write_seqcount_end(&files->fdt_seqcount);
>  		if (cur_fdt != &files->fdtab)
>  			call_rcu(&cur_fdt->rcu, free_fdtable_rcu);

Interesting.  AFAICS, your test doesn't step anywhere near that path,
does it?  So basically you never hit the retries during that...

  parent reply	other threads:[~2015-04-16 18:09 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-16 12:16 [RFC PATCH] fs: use a sequence counter instead of file_lock in fd_install Mateusz Guzik
2015-04-16 17:47 ` Eric Dumazet
2015-04-16 18:09 ` Al Viro [this message]
2015-04-16 20:42   ` Eric Dumazet
2015-04-16 20:55     ` Eric Dumazet
2015-04-16 22:00       ` Mateusz Guzik
2015-04-16 22:52         ` Eric Dumazet
2015-04-16 22:35   ` Mateusz Guzik
2015-04-17 21:46 ` Eric Dumazet
2015-04-17 22:16   ` Mateusz Guzik
2015-04-17 23:02     ` Al Viro
2015-04-18 19:41       ` Eric Dumazet
2015-04-20 13:41         ` Mateusz Guzik
2015-04-20 16:46           ` Eric Dumazet
2015-04-20 16:48             ` Eric Dumazet
2015-04-20 13:06       ` Mateusz Guzik
2015-04-20 13:43         ` Mateusz Guzik
2015-04-20 15:10           ` Mateusz Guzik
2015-04-20 17:15             ` Eric Dumazet
2015-04-20 20:49               ` Eric Dumazet
2015-04-21 18:05                 ` Eric Dumazet
2015-04-21 20:06                   ` Mateusz Guzik
2015-04-21 20:12                     ` Mateusz Guzik
2015-04-21 21:06                       ` Eric Dumazet
2015-04-22  4:59                         ` [PATCH] fs/file.c: don't acquire files->file_lock in fd_install() Eric Dumazet
2015-04-27 19:05                           ` Mateusz Guzik
2015-04-28 16:20                             ` Eric Dumazet
2015-04-29  4:25                           ` [PATCH v2] " Eric Dumazet
2015-06-22  2:32                             ` Al Viro
2015-06-23  5:31                               ` Eric Dumazet
2015-06-30 13:54                             ` [PATCH v3] " Eric Dumazet
2015-04-22 13:31                         ` [RFC PATCH] fs: use a sequence counter instead of file_lock in fd_install Mateusz Guzik
2015-04-22 13:55                           ` Eric Dumazet
2015-04-21 20:57                     ` Eric Dumazet

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