X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fmarker.c;h=b5a9fe1d50d5ce1c480ca7ca1777e55e6deb485e;hb=6f94f709b5b1d3a9b5f1ff7d4f3534de6cde3ff6;hp=48a4ea5afffde0b758a627fb63046f8a65976ff5;hpb=afbf331ed1252c85753ac6790356c11e171f3d0b;p=pandora-kernel.git diff --git a/kernel/marker.c b/kernel/marker.c index 48a4ea5afffd..b5a9fe1d50d5 100644 --- a/kernel/marker.c +++ b/kernel/marker.c @@ -23,12 +23,13 @@ #include #include #include +#include extern struct marker __start___markers[]; extern struct marker __stop___markers[]; /* Set to 1 to enable marker debug output */ -const int marker_debug; +static const int marker_debug; /* * markers_mutex nests inside module_mutex. Markers mutex protects the builtin @@ -104,18 +105,18 @@ 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 +134,7 @@ 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 +162,13 @@ 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 +184,7 @@ 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 +552,9 @@ 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 +566,8 @@ 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 +602,6 @@ 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 +672,9 @@ 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); @@ -717,6 +718,9 @@ int marker_probe_unregister(const char *name, 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; @@ -795,6 +799,9 @@ 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: