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Avoid calling _PHOLD(p1) with p2's lock held, since _PHOLD()

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may block to swap in p1.  Instead, call _PHOLD earlier, at a
point where the only lock held happens to be p1's.
This commit is contained in:
David Schultz 2004-10-01 05:01:29 +00:00
parent 616b5f90d3
commit 299bc7367d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=136005
1 changed files with 8 additions and 3 deletions
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11
sys/kern/kern_fork.c
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@ -533,8 +533,14 @@ fork1(td, flags, pages, procp)
* p_limit is copy-on-write. Bump its refcount.
*/
p2->p_limit = lim_hold(p1->p_limit);
PROC_UNLOCK(p1);
/*
* We don't need to prevent the parent from being swapped out just yet,
* but this is a convenient point to block to swap it in if needed.
*/
PROC_UNLOCK(p2);
_PHOLD(p1);
PROC_UNLOCK(p1);
/* Bump references to the text vnode (for procfs) */
if (p2->p_textvp)
@ -629,9 +635,8 @@ fork1(td, flags, pages, procp)
/*
* This begins the section where we must prevent the parent
* from being swapped.
* from being swapped. We already got a hold on the parent earlier.
*/
_PHOLD(p1);
PROC_UNLOCK(p1);
/*