From: "Vincent Catros" <Vincent.Catros@elios-informatique.fr>
To: "'David Woodhouse'" <dwmw2@infradead.org>
Cc: <ecos-discuss@sources.redhat.com>
Subject: [ECOS] RE : [ECOS] Is JFFS2 thread-safe?
Date: Thu, 27 Nov 2003 17:02:00 -0000 [thread overview]
Message-ID: <000e01c3b508$b6f34d30$7407a8c0@figuier> (raw)
In-Reply-To: <1069892845.14994.47.camel@imladris.demon.co.uk>
Davis,
> -----Message d'origine-----
> De : David Woodhouse [mailto:dwmw2@infradead.org]
> Envoyé : jeudi 27 novembre 2003 01:27
> À : Vincent Catros
> Cc : ecos-discuss@sources.redhat.com
> Objet : Re: [ECOS] Is JFFS2 thread-safe?
>
[...]
> In fact, I suspect that is actually OK because we set the
> CYG_SYNCMODE_FILE_FILESYSTEM flag and hence the fileio layer ensures
> that only one file system method is invoked at a time. It would be
> better to do our own locking and drop that flag though, since it makes
> coordinating the locking with gcthread.c a little nicer.
>
> Your underlying flash drivers may also need to be thread-safe, if
you're
> allowing concurrent calls into JFFS2 -- which I think we are; open and
> close are serialised but read() and write() on two separate files can
> happen simultaneously AFAICT.
[...]
Effectively, before any call to a file system function, the macro
LOCK_FS is called. This macro is an alias to cyg_fs_lock.
Accordig to the flag passed to that function (ie :
CYG_SYNCMODE_FILE_FILESYSTEM) file system functions are serialized that
way.
But it seems that read() and write() lead to a cyg_file_lock which call
cyg_fs_lock (see fd.cxx).
So, read() and write() are probably serialized to.
Am I wrong?
Regards.
Vincent
--
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next prev parent reply other threads:[~2003-11-27 17:02 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-26 9:15 Vincent Catros
2003-11-27 0:27 ` David Woodhouse
2003-11-27 9:12 ` [ECOS] RE : " Vincent Catros
2003-11-27 9:36 ` [ECOS] " David Woodhouse
2003-11-27 10:00 ` [ECOS] RE : " Vincent Catros
2003-11-27 10:24 ` [ECOS] " David Woodhouse
2003-11-28 11:14 ` [ECOS] " David Woodhouse
[not found] ` <1070018876.10048.35.camel@hades.cambridge.redhat.com>
2003-11-28 16:09 ` David Woodhouse
2003-11-29 14:54 ` Gary Thomas
2003-11-29 15:46 ` David Woodhouse
2003-11-29 15:47 ` Nick Garnett
2003-11-29 19:40 ` David Woodhouse
2003-11-27 17:02 ` Vincent Catros [this message]
2003-11-28 11:09 ` [ECOS] " David Woodhouse
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