linux-kernel - debugfs_create

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Date:	Fri, 18 Jul 2008 06:52:37 +0300
From:	Eduard - Gabriel Munteanu <eduard.munteanu@...ux360.ro>
To:	greg@...ah.com
Cc:	torvalds@...ux-foundation.org, Randy Dunlap <rdunlap@...otime.net>,
	linux-kernel@...r.kernel.org, Pekka Enberg <penberg@...helsinki.fi>
Subject: debugfs_create_u*() not SMP-safe

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

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