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From: Lubomir Rintel <lkundrak@v3.sk>
To: Kirill Smelkov <kirr@nexedi.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] *: convert stream-like files from nonseekable_open -> stream_open
Date: Wed, 27 Mar 2019 07:54:28 +0100
Message-ID: <93930d9c577a7cf83dc7c96ae411dec4d6d47610.camel@v3.sk> (raw)
In-Reply-To: <8794193f3040b798010970228d978c05ad56ec52.1553637462.git.kirr@nexedi.com>

On Tue, 2019-03-26 at 23:23 +0000, Kirill Smelkov wrote:
> Using scripts/coccinelle/api/stream_open.cocci added in the previous
> patch, search and convert to stream_open all in-kernel nonseekable_open
> users for which read and write actually do not depend on ppos and where
> there is no other methods in file_operations which assume @offset
> access.
> 
> I've verified each generated change manually - that it is correct to convert -
> and each other nonseekable_open instance left - that it is either not correct
> to convert there, or that it is not converted due to current stream_open.cocci
> limitations. The script also does not convert files that should be valid to
> convert, but that currently have .llseek = noop_llseek or generic_file_llseek
> for unknown reason despite file being opened with nonseekable_open (e.g.
> drivers/input/mousedev.c)
> 
> Among cases converted 14 were potentially vulnerable to read vs write deadlock
> (see details in the previous patch):

...

> and the reset were just safe to convert to stream_open because their
> read and write do not use ppos at all and corresponding file_operations
> do not have methods that assume @offset file access:

...

> 	drivers/char/pcmcia/scr24x_cs.c:95:8-24: WARNING: scr24x_fops: .read() and .write() have stream semantic; safe to change nonseekable_open -> stream_open.

...

> diff --git a/drivers/char/pcmcia/scr24x_cs.c b/drivers/char/pcmcia/scr24x_cs.c
> index f6b43d9350f0..04b39c3596cc 100644
> --- a/drivers/char/pcmcia/scr24x_cs.c
> +++ b/drivers/char/pcmcia/scr24x_cs.c
> @@ -92,7 +92,7 @@ static int scr24x_open(struct inode *inode, struct file *filp)
>  	kref_get(&dev->refcnt);
>  	filp->private_data = dev;
>  
> -	return nonseekable_open(inode, filp);
> +	return stream_open(inode, filp);
>  }
>  
>  static int scr24x_release(struct inode *inode, struct file *filp)

Acked-by: Lubomir Rintel <lkundrak@v3.sk> [scr24x_cs]

Thanks,
Lubo


  parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-26 22:20 [PATCH 1/3] fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock Kirill Smelkov
2019-03-26 23:22 ` [PATCH 3/3] fuse: Add FOPEN_STREAM and use stream_open() if filesystem returned that from open handler Kirill Smelkov
2019-04-24  7:13   ` [RESEND, PATCH " Kirill Smelkov
     [not found]     ` <20190424160611.2A71321900@mail.kernel.org>
2019-04-24 19:16       ` Kirill Smelkov
     [not found] ` <8794193f3040b798010970228d978c05ad56ec52.1553637462.git.kirr@nexedi.com>
2019-03-27  6:54   ` Lubomir Rintel [this message]
2019-03-27 16:58 ` [PATCH 1/3] fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock Juergen Gross
2019-04-06 17:07 ` Linus Torvalds
2019-04-07 20:04   ` Kirill Smelkov
2019-04-08  0:09     ` Linus Torvalds
2019-04-14  7:11       ` Kirill Smelkov
     [not found] ` <4c4651e2-167e-bfcc-7b3e-cda118f98a69@rasmusvillemoes.dk>
     [not found]   ` <20190409203807.GA13855@deco.navytux.spb.ru>
     [not found]     ` <d8c23d05-8810-13a2-cc50-7a47ff35e90b@rasmusvillemoes.dk>
2019-04-11 12:38       ` Kirill Smelkov
2019-04-11 16:22         ` Linus Torvalds
2019-04-12 12:42           ` Kirill Smelkov
2019-04-13 16:54             ` Kirill Smelkov
2019-04-13 16:54               ` [PATCH 1/2] vfs: pass ppos=NULL to .read()/.write() of FMODE_STREAM files Kirill Smelkov
2019-04-13 17:27                 ` Linus Torvalds
2019-04-13 17:38                   ` Al Viro
2019-04-13 18:44                   ` Kirill Smelkov
2019-04-13 16:55               ` [PATCH 2/2] vfs: use &file->f_pos directly on files that have position Kirill Smelkov

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