diff options
Diffstat (limited to 'kernel/marker.c')
| -rw-r--r-- | kernel/marker.c | 53 |
1 files changed, 30 insertions, 23 deletions
diff --git a/kernel/marker.c b/kernel/marker.c index c4c2cd8b61f..005b9595459 100644 --- a/kernel/marker.c +++ b/kernel/marker.c @@ -61,8 +61,8 @@ struct marker_entry { int refcount; /* Number of times armed. 0 if disarmed. */ struct rcu_head rcu; void *oldptr; - char rcu_pending:1; - char ptype:1; + unsigned char rcu_pending:1; + unsigned char ptype:1; char name[0]; /* Contains name'\0'format'\0' */ }; @@ -104,18 +104,18 @@ void marker_probe_cb(const struct marker *mdata, void *call_private, char ptype; /* - * disabling preemption to make sure the teardown of the callbacks can - * be done correctly when they are in modules and they insure RCU read - * coherency. + * preempt_disable does two things : disabling preemption to make sure + * the teardown of the callbacks can be done correctly when they are in + * modules and they insure RCU read coherency. */ preempt_disable(); - ptype = ACCESS_ONCE(mdata->ptype); + ptype = mdata->ptype; if (likely(!ptype)) { marker_probe_func *func; /* Must read the ptype before ptr. They are not data dependant, * so we put an explicit smp_rmb() here. */ smp_rmb(); - func = ACCESS_ONCE(mdata->single.func); + func = mdata->single.func; /* Must read the ptr before private data. They are not data * dependant, so we put an explicit smp_rmb() here. */ smp_rmb(); @@ -133,7 +133,7 @@ void marker_probe_cb(const struct marker *mdata, void *call_private, * in the fast path, so put the explicit barrier here. */ smp_read_barrier_depends(); - multi = ACCESS_ONCE(mdata->multi); + multi = mdata->multi; for (i = 0; multi[i].func; i++) { va_start(args, fmt); multi[i].func(multi[i].probe_private, call_private, fmt, @@ -161,13 +161,13 @@ void marker_probe_cb_noarg(const struct marker *mdata, char ptype; preempt_disable(); - ptype = ACCESS_ONCE(mdata->ptype); + ptype = mdata->ptype; if (likely(!ptype)) { marker_probe_func *func; /* Must read the ptype before ptr. They are not data dependant, * so we put an explicit smp_rmb() here. */ smp_rmb(); - func = ACCESS_ONCE(mdata->single.func); + func = mdata->single.func; /* Must read the ptr before private data. They are not data * dependant, so we put an explicit smp_rmb() here. */ smp_rmb(); @@ -183,7 +183,7 @@ void marker_probe_cb_noarg(const struct marker *mdata, * in the fast path, so put the explicit barrier here. */ smp_read_barrier_depends(); - multi = ACCESS_ONCE(mdata->multi); + multi = mdata->multi; for (i = 0; multi[i].func; i++) multi[i].func(multi[i].probe_private, call_private, fmt, &args); @@ -551,9 +551,9 @@ static int set_marker(struct marker_entry **entry, struct marker *elem, /* * Disable a marker and its probe callback. - * Note: only after a synchronize_sched() issued after setting elem->call to the - * empty function insures that the original callback is not used anymore. This - * insured by preemption disabling around the call site. + * Note: only waiting an RCU period after setting elem->call to the empty + * function insures that the original callback is not used anymore. This insured + * by preempt_disable around the call site. */ static void disable_marker(struct marker *elem) { @@ -565,8 +565,8 @@ static void disable_marker(struct marker *elem) elem->ptype = 0; /* single probe */ /* * Leave the private data and id there, because removal is racy and - * should be done only after a synchronize_sched(). These are never used - * until the next initialization anyway. + * should be done only after an RCU period. These are never used until + * the next initialization anyway. */ } @@ -601,9 +601,6 @@ void marker_update_probe_range(struct marker *begin, /* * Update probes, removing the faulty probes. - * Issues a synchronize_sched() when no reference to the module passed - * as parameter is found in the probes so the probe module can be - * safely unloaded from now on. * * Internal callback only changed before the first probe is connected to it. * Single probe private data can only be changed on 0 -> 1 and 2 -> 1 @@ -674,6 +671,9 @@ int marker_probe_register(const char *name, const char *format, entry->rcu_pending = 1; /* write rcu_pending before calling the RCU callback */ smp_wmb(); +#ifdef CONFIG_PREEMPT_RCU + synchronize_sched(); /* Until we have the call_rcu_sched() */ +#endif call_rcu(&entry->rcu, free_old_closure); end: mutex_unlock(&markers_mutex); @@ -698,14 +698,12 @@ int marker_probe_unregister(const char *name, { struct marker_entry *entry; struct marker_probe_closure *old; - int ret = 0; + int ret = -ENOENT; mutex_lock(&markers_mutex); entry = get_marker(name); - if (!entry) { - ret = -ENOENT; + if (!entry) goto end; - } if (entry->rcu_pending) rcu_barrier(); old = marker_entry_remove_probe(entry, probe, probe_private); @@ -713,12 +711,18 @@ int marker_probe_unregister(const char *name, marker_update_probes(); /* may update entry */ mutex_lock(&markers_mutex); entry = get_marker(name); + if (!entry) + goto end; entry->oldptr = old; entry->rcu_pending = 1; /* write rcu_pending before calling the RCU callback */ smp_wmb(); +#ifdef CONFIG_PREEMPT_RCU + synchronize_sched(); /* Until we have the call_rcu_sched() */ +#endif call_rcu(&entry->rcu, free_old_closure); remove_marker(name); /* Ignore busy error message */ + ret = 0; end: mutex_unlock(&markers_mutex); return ret; @@ -794,6 +798,9 @@ int marker_probe_unregister_private_data(marker_probe_func *probe, entry->rcu_pending = 1; /* write rcu_pending before calling the RCU callback */ smp_wmb(); +#ifdef CONFIG_PREEMPT_RCU + synchronize_sched(); /* Until we have the call_rcu_sched() */ +#endif call_rcu(&entry->rcu, free_old_closure); remove_marker(entry->name); /* Ignore busy error message */ end: |