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authorLinus Torvalds <torvalds@linux-foundation.org>2014-06-03 23:57:53 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-03 23:57:53 +0400
commit776edb59317ada867dfcddde40b55648beeb0078 (patch)
treef6a6136374642323cfefd7d6399ea429f9018ade /kernel
parent59a3d4c3631e553357b7305dc09db1990aa6757c (diff)
parent3cf2f34e1a3d4d5ff209d087925cf950e52f4805 (diff)
downloadlinux-776edb59317ada867dfcddde40b55648beeb0078.tar.xz
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next
Pull core locking updates from Ingo Molnar: "The main changes in this cycle were: - reduced/streamlined smp_mb__*() interface that allows more usecases and makes the existing ones less buggy, especially in rarer architectures - add rwsem implementation comments - bump up lockdep limits" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits) rwsem: Add comments to explain the meaning of the rwsem's count field lockdep: Increase static allocations arch: Mass conversion of smp_mb__*() arch,doc: Convert smp_mb__*() arch,xtensa: Convert smp_mb__*() arch,x86: Convert smp_mb__*() arch,tile: Convert smp_mb__*() arch,sparc: Convert smp_mb__*() arch,sh: Convert smp_mb__*() arch,score: Convert smp_mb__*() arch,s390: Convert smp_mb__*() arch,powerpc: Convert smp_mb__*() arch,parisc: Convert smp_mb__*() arch,openrisc: Convert smp_mb__*() arch,mn10300: Convert smp_mb__*() arch,mips: Convert smp_mb__*() arch,metag: Convert smp_mb__*() arch,m68k: Convert smp_mb__*() arch,m32r: Convert smp_mb__*() arch,ia64: Convert smp_mb__*() ...
Diffstat (limited to 'kernel')
-rw-r--r--kernel/debug/debug_core.c4
-rw-r--r--kernel/futex.c4
-rw-r--r--kernel/kmod.c2
-rw-r--r--kernel/locking/lockdep_internals.h6
-rw-r--r--kernel/locking/rwsem-xadd.c49
-rw-r--r--kernel/rcu/tree.c22
-rw-r--r--kernel/rcu/tree_plugin.h8
-rw-r--r--kernel/sched/core.c16
-rw-r--r--kernel/sched/cpupri.c6
-rw-r--r--kernel/sched/wait.c2
10 files changed, 92 insertions, 27 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 2956c8da1605..1adf62b39b96 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -534,7 +534,7 @@ return_normal:
kgdb_info[cpu].exception_state &=
~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
kgdb_info[cpu].enter_kgdb--;
- smp_mb__before_atomic_dec();
+ smp_mb__before_atomic();
atomic_dec(&slaves_in_kgdb);
dbg_touch_watchdogs();
local_irq_restore(flags);
@@ -662,7 +662,7 @@ kgdb_restore:
kgdb_info[cpu].exception_state &=
~(DCPU_WANT_MASTER | DCPU_IS_SLAVE);
kgdb_info[cpu].enter_kgdb--;
- smp_mb__before_atomic_dec();
+ smp_mb__before_atomic();
atomic_dec(&masters_in_kgdb);
/* Free kgdb_active */
atomic_set(&kgdb_active, -1);
diff --git a/kernel/futex.c b/kernel/futex.c
index 81dbe773ce4c..89bc9d59ac65 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -267,7 +267,7 @@ static inline void futex_get_mm(union futex_key *key)
* get_futex_key() implies a full barrier. This is relied upon
* as full barrier (B), see the ordering comment above.
*/
- smp_mb__after_atomic_inc();
+ smp_mb__after_atomic();
}
/*
@@ -280,7 +280,7 @@ static inline void hb_waiters_inc(struct futex_hash_bucket *hb)
/*
* Full barrier (A), see the ordering comment above.
*/
- smp_mb__after_atomic_inc();
+ smp_mb__after_atomic();
#endif
}
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 6b375af4958d..0ac67a5861c5 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -498,7 +498,7 @@ int __usermodehelper_disable(enum umh_disable_depth depth)
static void helper_lock(void)
{
atomic_inc(&running_helpers);
- smp_mb__after_atomic_inc();
+ smp_mb__after_atomic();
}
static void helper_unlock(void)
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index 4f560cfedc8f..51c4b24b6328 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -54,9 +54,9 @@ enum {
* table (if it's not there yet), and we check it for lock order
* conflicts and deadlocks.
*/
-#define MAX_LOCKDEP_ENTRIES 16384UL
+#define MAX_LOCKDEP_ENTRIES 32768UL
-#define MAX_LOCKDEP_CHAINS_BITS 15
+#define MAX_LOCKDEP_CHAINS_BITS 16
#define MAX_LOCKDEP_CHAINS (1UL << MAX_LOCKDEP_CHAINS_BITS)
#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
@@ -65,7 +65,7 @@ enum {
* Stack-trace: tightly packed array of stack backtrace
* addresses. Protected by the hash_lock.
*/
-#define MAX_STACK_TRACE_ENTRIES 262144UL
+#define MAX_STACK_TRACE_ENTRIES 524288UL
extern struct list_head all_lock_classes;
extern struct lock_chain lock_chains[];
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index 1d66e08e897d..b4219ff87b8c 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -12,6 +12,55 @@
#include <linux/export.h>
/*
+ * Guide to the rw_semaphore's count field for common values.
+ * (32-bit case illustrated, similar for 64-bit)
+ *
+ * 0x0000000X (1) X readers active or attempting lock, no writer waiting
+ * X = #active_readers + #readers attempting to lock
+ * (X*ACTIVE_BIAS)
+ *
+ * 0x00000000 rwsem is unlocked, and no one is waiting for the lock or
+ * attempting to read lock or write lock.
+ *
+ * 0xffff000X (1) X readers active or attempting lock, with waiters for lock
+ * X = #active readers + # readers attempting lock
+ * (X*ACTIVE_BIAS + WAITING_BIAS)
+ * (2) 1 writer attempting lock, no waiters for lock
+ * X-1 = #active readers + #readers attempting lock
+ * ((X-1)*ACTIVE_BIAS + ACTIVE_WRITE_BIAS)
+ * (3) 1 writer active, no waiters for lock
+ * X-1 = #active readers + #readers attempting lock
+ * ((X-1)*ACTIVE_BIAS + ACTIVE_WRITE_BIAS)
+ *
+ * 0xffff0001 (1) 1 reader active or attempting lock, waiters for lock
+ * (WAITING_BIAS + ACTIVE_BIAS)
+ * (2) 1 writer active or attempting lock, no waiters for lock
+ * (ACTIVE_WRITE_BIAS)
+ *
+ * 0xffff0000 (1) There are writers or readers queued but none active
+ * or in the process of attempting lock.
+ * (WAITING_BIAS)
+ * Note: writer can attempt to steal lock for this count by adding
+ * ACTIVE_WRITE_BIAS in cmpxchg and checking the old count
+ *
+ * 0xfffe0001 (1) 1 writer active, or attempting lock. Waiters on queue.
+ * (ACTIVE_WRITE_BIAS + WAITING_BIAS)
+ *
+ * Note: Readers attempt to lock by adding ACTIVE_BIAS in down_read and checking
+ * the count becomes more than 0 for successful lock acquisition,
+ * i.e. the case where there are only readers or nobody has lock.
+ * (1st and 2nd case above).
+ *
+ * Writers attempt to lock by adding ACTIVE_WRITE_BIAS in down_write and
+ * checking the count becomes ACTIVE_WRITE_BIAS for successful lock
+ * acquisition (i.e. nobody else has lock or attempts lock). If
+ * unsuccessful, in rwsem_down_write_failed, we'll check to see if there
+ * are only waiters but none active (5th case above), and attempt to
+ * steal the lock.
+ *
+ */
+
+/*
* Initialize an rwsem:
*/
void __init_rwsem(struct rw_semaphore *sem, const char *name,
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 3e3f13e8b429..f1ba77363fbb 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -458,9 +458,9 @@ static void rcu_eqs_enter_common(struct rcu_dynticks *rdtp, long long oldval,
}
rcu_prepare_for_idle(smp_processor_id());
/* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */
- smp_mb__before_atomic_inc(); /* See above. */
+ smp_mb__before_atomic(); /* See above. */
atomic_inc(&rdtp->dynticks);
- smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */
+ smp_mb__after_atomic(); /* Force ordering with next sojourn. */
WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);
/*
@@ -578,10 +578,10 @@ void rcu_irq_exit(void)
static void rcu_eqs_exit_common(struct rcu_dynticks *rdtp, long long oldval,
int user)
{
- smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */
+ smp_mb__before_atomic(); /* Force ordering w/previous sojourn. */
atomic_inc(&rdtp->dynticks);
/* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
- smp_mb__after_atomic_inc(); /* See above. */
+ smp_mb__after_atomic(); /* See above. */
WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
rcu_cleanup_after_idle(smp_processor_id());
trace_rcu_dyntick(TPS("End"), oldval, rdtp->dynticks_nesting);
@@ -706,10 +706,10 @@ void rcu_nmi_enter(void)
(atomic_read(&rdtp->dynticks) & 0x1))
return;
rdtp->dynticks_nmi_nesting++;
- smp_mb__before_atomic_inc(); /* Force delay from prior write. */
+ smp_mb__before_atomic(); /* Force delay from prior write. */
atomic_inc(&rdtp->dynticks);
/* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
- smp_mb__after_atomic_inc(); /* See above. */
+ smp_mb__after_atomic(); /* See above. */
WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
}
@@ -728,9 +728,9 @@ void rcu_nmi_exit(void)
--rdtp->dynticks_nmi_nesting != 0)
return;
/* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */
- smp_mb__before_atomic_inc(); /* See above. */
+ smp_mb__before_atomic(); /* See above. */
atomic_inc(&rdtp->dynticks);
- smp_mb__after_atomic_inc(); /* Force delay to next write. */
+ smp_mb__after_atomic(); /* Force delay to next write. */
WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);
}
@@ -2918,7 +2918,7 @@ void synchronize_sched_expedited(void)
s = atomic_long_read(&rsp->expedited_done);
if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) {
/* ensure test happens before caller kfree */
- smp_mb__before_atomic_inc(); /* ^^^ */
+ smp_mb__before_atomic(); /* ^^^ */
atomic_long_inc(&rsp->expedited_workdone1);
return;
}
@@ -2936,7 +2936,7 @@ void synchronize_sched_expedited(void)
s = atomic_long_read(&rsp->expedited_done);
if (ULONG_CMP_GE((ulong)s, (ulong)firstsnap)) {
/* ensure test happens before caller kfree */
- smp_mb__before_atomic_inc(); /* ^^^ */
+ smp_mb__before_atomic(); /* ^^^ */
atomic_long_inc(&rsp->expedited_workdone2);
return;
}
@@ -2965,7 +2965,7 @@ void synchronize_sched_expedited(void)
s = atomic_long_read(&rsp->expedited_done);
if (ULONG_CMP_GE((ulong)s, (ulong)snap)) {
/* ensure test happens before caller kfree */
- smp_mb__before_atomic_inc(); /* ^^^ */
+ smp_mb__before_atomic(); /* ^^^ */
atomic_long_inc(&rsp->expedited_done_lost);
break;
}
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 29977ae84e7e..cbc2c45265e2 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2462,9 +2462,9 @@ static void rcu_sysidle_enter(struct rcu_dynticks *rdtp, int irq)
/* Record start of fully idle period. */
j = jiffies;
ACCESS_ONCE(rdtp->dynticks_idle_jiffies) = j;
- smp_mb__before_atomic_inc();
+ smp_mb__before_atomic();
atomic_inc(&rdtp->dynticks_idle);
- smp_mb__after_atomic_inc();
+ smp_mb__after_atomic();
WARN_ON_ONCE(atomic_read(&rdtp->dynticks_idle) & 0x1);
}
@@ -2529,9 +2529,9 @@ static void rcu_sysidle_exit(struct rcu_dynticks *rdtp, int irq)
}
/* Record end of idle period. */
- smp_mb__before_atomic_inc();
+ smp_mb__before_atomic();
atomic_inc(&rdtp->dynticks_idle);
- smp_mb__after_atomic_inc();
+ smp_mb__after_atomic();
WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks_idle) & 0x1));
/*
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 71d9a9c93954..a62a7dec3986 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -90,6 +90,22 @@
#define CREATE_TRACE_POINTS
#include <trace/events/sched.h>
+#ifdef smp_mb__before_atomic
+void __smp_mb__before_atomic(void)
+{
+ smp_mb__before_atomic();
+}
+EXPORT_SYMBOL(__smp_mb__before_atomic);
+#endif
+
+#ifdef smp_mb__after_atomic
+void __smp_mb__after_atomic(void)
+{
+ smp_mb__after_atomic();
+}
+EXPORT_SYMBOL(__smp_mb__after_atomic);
+#endif
+
void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period)
{
unsigned long delta;
diff --git a/kernel/sched/cpupri.c b/kernel/sched/cpupri.c
index 8834243abee2..981fcd7dc394 100644
--- a/kernel/sched/cpupri.c
+++ b/kernel/sched/cpupri.c
@@ -165,7 +165,7 @@ void cpupri_set(struct cpupri *cp, int cpu, int newpri)
* do a write memory barrier, and then update the count, to
* make sure the vector is visible when count is set.
*/
- smp_mb__before_atomic_inc();
+ smp_mb__before_atomic();
atomic_inc(&(vec)->count);
do_mb = 1;
}
@@ -185,14 +185,14 @@ void cpupri_set(struct cpupri *cp, int cpu, int newpri)
* the new priority vec.
*/
if (do_mb)
- smp_mb__after_atomic_inc();
+ smp_mb__after_atomic();
/*
* When removing from the vector, we decrement the counter first
* do a memory barrier and then clear the mask.
*/
atomic_dec(&(vec)->count);
- smp_mb__after_atomic_inc();
+ smp_mb__after_atomic();
cpumask_clear_cpu(cpu, vec->mask);
}
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 7d50f794e248..0ffa20ae657b 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -394,7 +394,7 @@ EXPORT_SYMBOL(__wake_up_bit);
*
* In order for this to function properly, as it uses waitqueue_active()
* internally, some kind of memory barrier must be done prior to calling
- * this. Typically, this will be smp_mb__after_clear_bit(), but in some
+ * this. Typically, this will be smp_mb__after_atomic(), but in some
* cases where bitflags are manipulated non-atomically under a lock, one
* may need to use a less regular barrier, such fs/inode.c's smp_mb(),
* because spin_unlock() does not guarantee a memory barrier.