* [QUESTION] MOD_INC/MOD_DEC: useful to check for correct usage?
@ 2001-04-05 1:25 Dawson Engler
2001-04-05 1:34 ` Alexander Viro
2001-04-23 22:57 ` Keith Owens
0 siblings, 2 replies; 3+ messages in thread
From: Dawson Engler @ 2001-04-05 1:25 UTC (permalink / raw)
To: linux-kernel
Hi,
in the old days you couldn't call a sleeping function in a module
before doing a MOD_INC or after doing a MOD_DEC. Then some safety nets
were added that made these obsolete (in some number of places). I was
told that people had decided to potentially get rid of all safety
nets. Is this true? Is it worthwhile to have a checker for these two
rules?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [QUESTION] MOD_INC/MOD_DEC: useful to check for correct usage?
2001-04-05 1:25 [QUESTION] MOD_INC/MOD_DEC: useful to check for correct usage? Dawson Engler
@ 2001-04-05 1:34 ` Alexander Viro
2001-04-23 22:57 ` Keith Owens
1 sibling, 0 replies; 3+ messages in thread
From: Alexander Viro @ 2001-04-05 1:34 UTC (permalink / raw)
To: Dawson Engler; +Cc: linux-kernel
On Wed, 4 Apr 2001, Dawson Engler wrote:
> Hi,
>
> in the old days you couldn't call a sleeping function in a module
> before doing a MOD_INC or after doing a MOD_DEC. Then some safety nets
> were added that made these obsolete (in some number of places). I was
> told that people had decided to potentially get rid of all safety
> nets. Is this true? Is it worthwhile to have a checker for these two
> rules?
It's worth removing the MOD_{INC,DEC}_USE_COUNT. Which had been done
in quite a few places. Let the caller handle the refcount on callee -
_that_ is definitely safe.
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [QUESTION] MOD_INC/MOD_DEC: useful to check for correct usage?
2001-04-05 1:25 [QUESTION] MOD_INC/MOD_DEC: useful to check for correct usage? Dawson Engler
2001-04-05 1:34 ` Alexander Viro
@ 2001-04-23 22:57 ` Keith Owens
1 sibling, 0 replies; 3+ messages in thread
From: Keith Owens @ 2001-04-23 22:57 UTC (permalink / raw)
To: Dawson Engler; +Cc: linux-kernel
On Wed, 4 Apr 2001 18:25:08 -0700 (PDT),
Dawson Engler <engler@csl.Stanford.EDU> wrote:
>in the old days you couldn't call a sleeping function in a module
>before doing a MOD_INC or after doing a MOD_DEC. Then some safety nets
>were added that made these obsolete (in some number of places). I was
>told that people had decided to potentially get rid of all safety
>nets. Is this true? Is it worthwhile to have a checker for these two
>rules?
I expect to reintroduce the MOD_{INC,DEC} rules in 2.5. Al Viro's
patches to bump the module use count in the caller work up to a point
but they are not a complete fix. You cannot bump the module use count
from an interrupt, which causes problem for netfilter (ask Rusty for
details).
A module can have multiple associated areas including the code segment,
the exception table and arch specific data like the IA64 unwind lists.
Al Viro's fix does not cover all of these areas, Alan Cox added a
spinlock for the exception table but nothing covers the arch specific
data. Adding more spinlocks is not the answer, it penalizes the
mainline code to guard against an unusual event (module unload).
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2001-04-23 22:59 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2001-04-05 1:25 [QUESTION] MOD_INC/MOD_DEC: useful to check for correct usage? Dawson Engler
2001-04-05 1:34 ` Alexander Viro
2001-04-23 22:57 ` Keith Owens
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox