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From: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
To: greg@kroah.com
Cc: torvalds@linux-foundation.org,
	Randy Dunlap <rdunlap@xenotime.net>,
	linux-kernel@vger.kernel.org,
	Pekka Enberg <penberg@cs.helsinki.fi>
Subject: debugfs_create_u*() not SMP-safe
Date: Fri, 18 Jul 2008 06:52:37 +0300	[thread overview]
Message-ID: <20080718035237.GA7744@localhost> (raw)

Hi,

I noticed debugfs_create_u*() functions don't allow for any precautions
to be taken while doing r/w to the exported variables. Thus any export of a
variable isn't SMP-safe.

As far as I can tell, this only works safely for constant data. Let me
ask then, what is the purpose of these functions? Are they intended only
for unreliable data?

As I see it, they could be replaced by one of the following:
- Have them only export atomic data, that is atomic_t variables.
- Have them take a lock as a parameter, which the read() / write()
  handler grabs. The kernel code that exported the variable should also
  do r/w while holding that same lock.

Or am I wrong?


	Thanks,
	Eduard


             reply	other threads:[~2008-07-18  3:54 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-07-18  3:52 Eduard - Gabriel Munteanu [this message]
2008-07-18 18:46 ` debugfs_create_u*() not SMP-safe Greg KH

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