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Bound the number of iterations a thread can perform inside

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ktr_resize_pool(); this eliminates a potential livelock.

Return ENOSPC only if we encountered an out-of-memory condition when
trying to increase the pool size.

Reviewed by:	jhb, bde (style)
This commit is contained in:
Joseph Koshy 2003-11-11 09:09:26 +00:00
parent f27ec812b6
commit a5896914f0
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=122478
1 changed files with 8 additions and 6 deletions
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14
sys/kern/kern_ktrace.c
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@ -168,7 +168,7 @@ sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS)
error = SYSCTL_OUT(req, &oldsize, sizeof(u_int));
if (error)
return (error);
if (newsize != wantsize)
if (wantsize > oldsize && newsize < wantsize)
return (ENOSPC);
return (0);
}
@ -179,14 +179,16 @@ static u_int
ktrace_resize_pool(u_int newsize)
{
struct ktr_request *req;
int bound;
mtx_assert(&ktrace_mtx, MA_OWNED);
print_message = 1;
if (newsize == ktr_requestpool)
return (newsize);
if (newsize < ktr_requestpool)
bound = newsize - ktr_requestpool;
if (bound == 0)
return (ktr_requestpool);
if (bound < 0)
/* Shrink pool down to newsize if possible. */
while (ktr_requestpool > newsize) {
while (bound++ < 0) {
req = STAILQ_FIRST(&ktr_free);
if (req == NULL)
return (ktr_requestpool);
@ -198,7 +200,7 @@ ktrace_resize_pool(u_int newsize)
}
else
/* Grow pool up to newsize. */
while (ktr_requestpool < newsize) {
while (bound-- > 0) {
mtx_unlock(&ktrace_mtx);
req = malloc(sizeof(struct ktr_request), M_KTRACE,
M_WAITOK);