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authorLinus Torvalds <torvalds@linux-foundation.org>2013-02-19 17:45:20 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-19 17:45:20 -0800
commite84cf5d0fd53badf3a93c790e280cc92a69ed999 (patch)
treeabc4d04bc31e5682794d1ea90c38cfeb4d5c9b97 /include
parent19f949f52599ba7c3f67a5897ac6be14bfcb1200 (diff)
parentac0e32024b8f40987b3db7d2defdc6b5153ba354 (diff)
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU changes from Ingo Molnar: "SRCU changes: - These include debugging aids, updates that move towards the goal of permitting srcu_read_lock() and srcu_read_unlock() to be used from idle and offline CPUs, and a few small fixes. Changes to rcutorture and to RCU documentation: - Posted to LKML at https://lkml.org/lkml/2013/1/26/188 Enhancements to uniprocessor handling in tiny RCU: - Posted to LKML at https://lkml.org/lkml/2013/1/27/2 Tag RCU callbacks with grace-period number to simplify callback advancement: - Posted to LKML at https://lkml.org/lkml/2013/1/26/203 Miscellaneous fixes: - Posted to LKML at https://lkml.org/lkml/2013/1/26/204" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) srcu: use ACCESS_ONCE() to access sp->completed in srcu_read_lock() srcu: Update synchronize_srcu_expedited()'s comments srcu: Update synchronize_srcu()'s comments srcu: Remove checks preventing idle CPUs from calling srcu_read_lock() srcu: Remove checks preventing offline CPUs from calling srcu_read_lock() srcu: Simple cleanup for cleanup_srcu_struct() srcu: Add might_sleep() annotation to synchronize_srcu() srcu: Simplify __srcu_read_unlock() via this_cpu_dec() rcu: Allow rcutorture to be built at low optimization levels rcu: Make rcutorture's shuffler task shuffle recently added tasks rcu: Allow TREE_PREEMPT_RCU on UP systems rcu: Provide RCU CPU stall warnings for tiny RCU context_tracking: Add comments on interface and internals rcu: Remove obsolete Kconfig option from comment rcu: Remove unused code originally used for context tracking rcu: Consolidate debugging Kconfig options rcu: Correct 'optimized' to 'optimize' in header comment rcu: Trace callback acceleration rcu: Tag callback lists with corresponding grace-period number rcutorture: Don't compare ptr with 0 ...
Diffstat (limited to 'include')
-rw-r--r--include/linux/rcupdate.h15
-rw-r--r--include/linux/srcu.h26
-rw-r--r--include/trace/events/rcu.h31
3 files changed, 35 insertions, 37 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 275aa3f1062..b758ce17b30 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -53,7 +53,10 @@ extern int rcutorture_runnable; /* for sysctl */
extern void rcutorture_record_test_transition(void);
extern void rcutorture_record_progress(unsigned long vernum);
extern void do_trace_rcu_torture_read(char *rcutorturename,
- struct rcu_head *rhp);
+ struct rcu_head *rhp,
+ unsigned long secs,
+ unsigned long c_old,
+ unsigned long c);
#else
static inline void rcutorture_record_test_transition(void)
{
@@ -63,9 +66,13 @@ static inline void rcutorture_record_progress(unsigned long vernum)
}
#ifdef CONFIG_RCU_TRACE
extern void do_trace_rcu_torture_read(char *rcutorturename,
- struct rcu_head *rhp);
+ struct rcu_head *rhp,
+ unsigned long secs,
+ unsigned long c_old,
+ unsigned long c);
#else
-#define do_trace_rcu_torture_read(rcutorturename, rhp) do { } while (0)
+#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
+ do { } while (0)
#endif
#endif
@@ -749,7 +756,7 @@ static inline void rcu_preempt_sleep_check(void)
* preemptible RCU implementations (TREE_PREEMPT_RCU and TINY_PREEMPT_RCU)
* in CONFIG_PREEMPT kernel builds, RCU read-side critical sections may
* be preempted, but explicit blocking is illegal. Finally, in preemptible
- * RCU implementations in real-time (CONFIG_PREEMPT_RT) kernel builds,
+ * RCU implementations in real-time (with -rt patchset) kernel builds,
* RCU read-side critical sections may be preempted and they may also
* block, but only when acquiring spinlocks that are subject to priority
* inheritance.
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 6eb691b0835..04f4121a23a 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -151,30 +151,14 @@ void srcu_barrier(struct srcu_struct *sp);
* Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
* and while lockdep is disabled.
*
- * Note that if the CPU is in the idle loop from an RCU point of view
- * (ie: that we are in the section between rcu_idle_enter() and
- * rcu_idle_exit()) then srcu_read_lock_held() returns false even if
- * the CPU did an srcu_read_lock(). The reason for this is that RCU
- * ignores CPUs that are in such a section, considering these as in
- * extended quiescent state, so such a CPU is effectively never in an
- * RCU read-side critical section regardless of what RCU primitives it
- * invokes. This state of affairs is required --- we need to keep an
- * RCU-free window in idle where the CPU may possibly enter into low
- * power mode. This way we can notice an extended quiescent state to
- * other CPUs that started a grace period. Otherwise we would delay any
- * grace period as long as we run in the idle task.
- *
- * Similarly, we avoid claiming an SRCU read lock held if the current
- * CPU is offline.
+ * Note that SRCU is based on its own statemachine and it doesn't
+ * relies on normal RCU, it can be called from the CPU which
+ * is in the idle loop from an RCU point of view or offline.
*/
static inline int srcu_read_lock_held(struct srcu_struct *sp)
{
if (!debug_lockdep_rcu_enabled())
return 1;
- if (rcu_is_cpu_idle())
- return 0;
- if (!rcu_lockdep_current_cpu_online())
- return 0;
return lock_is_held(&sp->dep_map);
}
@@ -236,8 +220,6 @@ static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
int retval = __srcu_read_lock(sp);
rcu_lock_acquire(&(sp)->dep_map);
- rcu_lockdep_assert(!rcu_is_cpu_idle(),
- "srcu_read_lock() used illegally while idle");
return retval;
}
@@ -251,8 +233,6 @@ static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
__releases(sp)
{
- rcu_lockdep_assert(!rcu_is_cpu_idle(),
- "srcu_read_unlock() used illegally while idle");
rcu_lock_release(&(sp)->dep_map);
__srcu_read_unlock(sp, idx);
}
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index d4f559b1ec3..1918e832da4 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -44,8 +44,10 @@ TRACE_EVENT(rcu_utilization,
* of a new grace period or the end of an old grace period ("cpustart"
* and "cpuend", respectively), a CPU passing through a quiescent
* state ("cpuqs"), a CPU coming online or going offline ("cpuonl"
- * and "cpuofl", respectively), and a CPU being kicked for being too
- * long in dyntick-idle mode ("kick").
+ * and "cpuofl", respectively), a CPU being kicked for being too
+ * long in dyntick-idle mode ("kick"), a CPU accelerating its new
+ * callbacks to RCU_NEXT_READY_TAIL ("AccReadyCB"), and a CPU
+ * accelerating its new callbacks to RCU_WAIT_TAIL ("AccWaitCB").
*/
TRACE_EVENT(rcu_grace_period,
@@ -393,7 +395,7 @@ TRACE_EVENT(rcu_kfree_callback,
*/
TRACE_EVENT(rcu_batch_start,
- TP_PROTO(char *rcuname, long qlen_lazy, long qlen, int blimit),
+ TP_PROTO(char *rcuname, long qlen_lazy, long qlen, long blimit),
TP_ARGS(rcuname, qlen_lazy, qlen, blimit),
@@ -401,7 +403,7 @@ TRACE_EVENT(rcu_batch_start,
__field(char *, rcuname)
__field(long, qlen_lazy)
__field(long, qlen)
- __field(int, blimit)
+ __field(long, blimit)
),
TP_fast_assign(
@@ -411,7 +413,7 @@ TRACE_EVENT(rcu_batch_start,
__entry->blimit = blimit;
),
- TP_printk("%s CBs=%ld/%ld bl=%d",
+ TP_printk("%s CBs=%ld/%ld bl=%ld",
__entry->rcuname, __entry->qlen_lazy, __entry->qlen,
__entry->blimit)
);
@@ -523,22 +525,30 @@ TRACE_EVENT(rcu_batch_end,
*/
TRACE_EVENT(rcu_torture_read,
- TP_PROTO(char *rcutorturename, struct rcu_head *rhp),
+ TP_PROTO(char *rcutorturename, struct rcu_head *rhp,
+ unsigned long secs, unsigned long c_old, unsigned long c),
- TP_ARGS(rcutorturename, rhp),
+ TP_ARGS(rcutorturename, rhp, secs, c_old, c),
TP_STRUCT__entry(
__field(char *, rcutorturename)
__field(struct rcu_head *, rhp)
+ __field(unsigned long, secs)
+ __field(unsigned long, c_old)
+ __field(unsigned long, c)
),
TP_fast_assign(
__entry->rcutorturename = rcutorturename;
__entry->rhp = rhp;
+ __entry->secs = secs;
+ __entry->c_old = c_old;
+ __entry->c = c;
),
- TP_printk("%s torture read %p",
- __entry->rcutorturename, __entry->rhp)
+ TP_printk("%s torture read %p %luus c: %lu %lu",
+ __entry->rcutorturename, __entry->rhp,
+ __entry->secs, __entry->c_old, __entry->c)
);
/*
@@ -608,7 +618,8 @@ TRACE_EVENT(rcu_barrier,
#define trace_rcu_invoke_kfree_callback(rcuname, rhp, offset) do { } while (0)
#define trace_rcu_batch_end(rcuname, callbacks_invoked, cb, nr, iit, risk) \
do { } while (0)
-#define trace_rcu_torture_read(rcutorturename, rhp) do { } while (0)
+#define trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
+ do { } while (0)
#define trace_rcu_barrier(name, s, cpu, cnt, done) do { } while (0)
#endif /* #else #ifdef CONFIG_RCU_TRACE */