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Code Issues Releases Activity

Move the atomic() mbstat.m_drops incrementing to the MGET(HDR) and

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MCLGET macros in order to avoid incrementing the drop count twice.
Otherwise, in some cases, we may increment m_drops once in m_mballoc()
for example, and increment it again in m_mballoc_wait() if the
wait fails.
This commit is contained in:
Bosko Milekic 2001-03-24 23:47:52 +00:00
parent 66ef8af5b0
commit 2ba1a89559
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=74764
2 changed files with 13 additions and 22 deletions
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24
sys/kern/uipc_mbuf.c
View File

@ -245,16 +245,8 @@ m_mballoc(int nmb, int how)
* Also, once we run out of map space, it will be impossible to
* get any more (nothing is ever freed back to the map).
*/
if (mb_map_full || ((nmb + mbstat.m_mbufs) > nmbufs)) {
/*
* Needs to be atomic as we may be incrementing it
* while holding another mutex, like mclfree. In other
* words, m_drops is not reserved solely for mbufs,
* but is also available for clusters.
*/
atomic_add_long(&mbstat.m_drops, 1);
if (mb_map_full || ((nmb + mbstat.m_mbufs) > nmbufs))
return (0);
}
mtx_unlock(&mmbfree.m_mtx);
p = (caddr_t)kmem_malloc(mb_map, nbytes, M_NOWAIT);
@ -343,8 +335,7 @@ m_mballoc_wait(void)
atomic_add_long(&mbstat.m_wait, 1);
if (mmbfree.m_head != NULL)
MBWAKEUP(m_mballoc_wid);
} else
atomic_add_long(&mbstat.m_drops, 1);
}
return (p);
}
@ -370,10 +361,8 @@ m_clalloc(int ncl, int how)
* If we've hit the mcluster number limit, stop allocating from
* mb_map.
*/
if (mb_map_full || ((ncl + mbstat.m_clusters) > nmbclusters)) {
atomic_add_long(&mbstat.m_drops, 1);
if (mb_map_full || ((ncl + mbstat.m_clusters) > nmbclusters))
return (0);
}
mtx_unlock(&mclfree.m_mtx);
p = (caddr_t)kmem_malloc(mb_map, npg_sz,
@ -384,10 +373,8 @@ m_clalloc(int ncl, int how)
* Either the map is now full, or `how' is M_DONTWAIT and there
* are no pages left.
*/
if (p == NULL) {
atomic_add_long(&mbstat.m_drops, 1);
if (p == NULL)
return (0);
}
/*
* We don't let go of the mutex in order to avoid a race.
@ -429,8 +416,7 @@ m_clalloc_wait(void)
atomic_add_long(&mbstat.m_wait, 1);
if (mclfree.m_head != NULL)
MBWAKEUP(m_clalloc_wid);
} else
atomic_add_long(&mbstat.m_drops, 1);
}
return (p);
}

11
sys/sys/mbuf.h
View File

@ -377,8 +377,10 @@ struct mcntfree_lst {
mbtypes[_mtype]++; \
mtx_unlock(&mmbfree.m_mtx); \
_MGET_SETUP(_mm, _mtype); \
} else \
} else { \
mtx_unlock(&mmbfree.m_mtx); \
atomic_add_long(&mbstat.m_drops, 1); \
} \
(m) = _mm; \
} while (0)
@ -404,8 +406,10 @@ struct mcntfree_lst {
mbtypes[_mtype]++; \
mtx_unlock(&mmbfree.m_mtx); \
_MGETHDR_SETUP(_mm, _mtype); \
} else \
} else { \
mtx_unlock(&mmbfree.m_mtx); \
atomic_add_long(&mbstat.m_drops, 1); \
} \
(m) = _mm; \
} while (0)
@ -453,7 +457,8 @@ struct mcntfree_lst {
_mm->m_ext.ext_size = MCLBYTES; \
_mm->m_ext.ext_type = EXT_CLUSTER; \
} \
} \
} else \
atomic_add_long(&mbstat.m_drops, 1); \
} while (0)
#define MEXTADD(m, buf, size, free, args, flags, type) do { \