Author: davide
Date: Fri Sep 20 23:16:15 2013
New Revision: 255747
URL: http://svnweb.freebsd.org/changeset/base/255747
Log:
Fix callout_init_rm() in the shared case, allocating storage for 'struct
rm_priotracker' directly in the softclock thread. Now consumers can
pass CALLOUT_SHAREDLOCK flag to callout initialization routine safely.
The choice of the already existing flags instead of special casing
shared rmlocks is done to prevent consumer footshooting.
Suggested by: jhb
Reviewed by: jhb
Approved by: re (delphij)
Modified:
head/sys/kern/kern_timeout.c
Modified: head/sys/kern/kern_timeout.c
==============================================================================
--- head/sys/kern/kern_timeout.c Fri Sep 20 23:10:52 2013
(r255746)
+++ head/sys/kern/kern_timeout.c Fri Sep 20 23:16:15 2013
(r255747)
@@ -597,11 +597,13 @@ softclock_call_cc(struct callout *c, str
#endif
int direct)
{
+ struct rm_priotracker tracker;
void (*c_func)(void *);
void *c_arg;
struct lock_class *class;
struct lock_object *c_lock;
- int c_flags, sharedlock;
+ uintptr_t lock_status;
+ int c_flags;
#ifdef SMP
struct callout_cpu *new_cc;
void (*new_func)(void *);
@@ -620,7 +622,13 @@ softclock_call_cc(struct callout *c, str
(CALLOUT_PENDING | CALLOUT_ACTIVE),
("softclock_call_cc: pend|act %p %x", c, c->c_flags));
class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL;
- sharedlock = (c->c_flags & CALLOUT_SHAREDLOCK) ? 0 : 1;
+ lock_status = 0;
+ if (c->c_flags & CALLOUT_SHAREDLOCK) {
+ if (class == &lock_class_rm)
+ lock_status = (uintptr_t)&tracker;
+ else
+ lock_status = 1;
+ }
c_lock = c->c_lock;
c_func = c->c_func;
c_arg = c->c_arg;
@@ -633,7 +641,7 @@ softclock_call_cc(struct callout *c, str
cc->cc_exec_entity[direct].cc_cancel = false;
CC_UNLOCK(cc);
if (c_lock != NULL) {
- class->lc_lock(c_lock, sharedlock);
+ class->lc_lock(c_lock, lock_status);
/*
* The callout may have been cancelled
* while we switched locks.
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