project-base/server-skynet-source-3rd-jemalloc
2
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fix a heap dumping deadlock.

Browse Source 
Restructure the ctx initialization code such that the ctx isn't locked
across portions of the initialization code where allocation could occur.
Instead artificially inflate the cnt_merged.curobjs field, just as is
done elsewhere to avoid similar races to the one that would otherwise be
created by the reduction in locking scope.

This bug affected interval- and growth-triggered heap dumping, but not
manual heap dumping.
This commit is contained in:
Jason Evans 2011-01-14 17:27:44 -08:00
parent 624f2f3cc9
commit 10e4523094
1 changed files with 22 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
jemalloc/src/prof.c
View File

@ -432,6 +432,7 @@ prof_lookup(prof_bt_t *bt)
prof_ctx_t *p; prof_ctx_t *p;
void *v; void *v;
} ctx; } ctx;
bool new_ctx;
/* /*
* This thread's cache lacks bt. Look for it in the global * This thread's cache lacks bt. Look for it in the global
@ -468,12 +469,14 @@ prof_lookup(prof_bt_t *bt)
idalloc(ctx.v); idalloc(ctx.v);
return (NULL); return (NULL);
} }
} /*
/* * Artificially raise curobjs, in order to avoid a race
* Acquire ctx's lock before releasing bt2ctx_mtx, in order to * condition with prof_ctx_merge()/prof_ctx_destroy().
* avoid a race condition with prof_ctx_destroy(). */
*/ ctx.p->cnt_merged.curobjs++;
malloc_mutex_lock(&ctx.p->lock); new_ctx = true;
} else
new_ctx = false;
prof_leave(); prof_leave();
/* Link a prof_thd_cnt_t into ctx for this thread. */ /* Link a prof_thd_cnt_t into ctx for this thread. */
@ -498,7 +501,11 @@ prof_lookup(prof_bt_t *bt)
/* Allocate and partially initialize a new cnt. */ /* Allocate and partially initialize a new cnt. */
ret.v = imalloc(sizeof(prof_thr_cnt_t)); ret.v = imalloc(sizeof(prof_thr_cnt_t));
if (ret.p == NULL) { if (ret.p == NULL) {
malloc_mutex_unlock(&ctx.p->lock); if (new_ctx) {
malloc_mutex_lock(&ctx.p->lock);
ctx.p->cnt_merged.curobjs--;
malloc_mutex_unlock(&ctx.p->lock);
}
return (NULL); return (NULL);
} }
ql_elm_new(ret.p, cnts_link); ql_elm_new(ret.p, cnts_link);
@ -509,12 +516,19 @@ prof_lookup(prof_bt_t *bt)
ret.p->epoch = 0; ret.p->epoch = 0;
memset(&ret.p->cnts, 0, sizeof(prof_cnt_t)); memset(&ret.p->cnts, 0, sizeof(prof_cnt_t));
if (ckh_insert(&prof_tdata->bt2cnt, btkey.v, ret.v)) { if (ckh_insert(&prof_tdata->bt2cnt, btkey.v, ret.v)) {
malloc_mutex_unlock(&ctx.p->lock); if (new_ctx) {
malloc_mutex_lock(&ctx.p->lock);
ctx.p->cnt_merged.curobjs--;
malloc_mutex_unlock(&ctx.p->lock);
}
idalloc(ret.v); idalloc(ret.v);
return (NULL); return (NULL);
} }
ql_head_insert(&prof_tdata->lru_ql, ret.p, lru_link); ql_head_insert(&prof_tdata->lru_ql, ret.p, lru_link);
malloc_mutex_lock(&ctx.p->lock);
ql_tail_insert(&ctx.p->cnts_ql, ret.p, cnts_link); ql_tail_insert(&ctx.p->cnts_ql, ret.p, cnts_link);
if (new_ctx)
ctx.p->cnt_merged.curobjs--;
malloc_mutex_unlock(&ctx.p->lock); malloc_mutex_unlock(&ctx.p->lock);
} else { } else {
/* Move ret to the front of the LRU. */ /* Move ret to the front of the LRU. */