user/sven/linux.git/kernel/rcu/srcu.c, branch v4.4.153

rcu: Move preemption disabling out of __srcu_read_lock()

2015-10-06T18:15:43Z

Currently, __srcu_read_lock() cannot be invoked from restricted environments because it contains calls to preempt_disable() and preempt_enable(), both of which can invoke lockdep, which is a bad idea in some restricted execution modes. This commit therefore moves the preempt_disable() and preempt_enable() from __srcu_read_lock() to srcu_read_lock(). It also inserts the preempt_disable() and preempt_enable() around the call to __srcu_read_lock() in do_exit(). Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

rcu: Use rcu_callback_t in call_rcu*() and friends

2015-10-06T18:08:05Z

As we now have rcu_callback_t typedefs as the type of rcu callbacks, we should use it in call_rcu*() and friends as the type of parameters. This could save us a few lines of code and make it clear which function requires an rcu callbacks rather than other callbacks as its argument. Besides, this can also help cscope to generate a better database for code reading. Signed-off-by: Boqun Feng Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()

2015-07-22T22:27:32Z

This commit renames rcu_lockdep_assert() to RCU_LOCKDEP_WARN() for consistency with the WARN() series of macros. This also requires inverting the sense of the conditional, which this commit also does. Reported-by: Ingo Molnar Signed-off-by: Paul E. McKenney Reviewed-by: Ingo Molnar

rcu: Change return type to bool

2015-07-15T21:43:53Z

Type-checking coccinelle spatches are being used to locate type mismatches between function signatures and return values in this case this produced: ./kernel/rcu/srcu.c:271 WARNING: return of wrong type int != unsigned long, srcu_readers_active() returns an int that is the sum of per_cpu unsigned long but the only user is cleanup_srcu_struct() which is using it as a boolean (condition) to see if there is any readers rather than actually using the approximate number of readers. The theoretically possible unsigned long overflow case does not need to be handled explicitly - if we had 4G++ readers then something else went wrong a long time ago. proposal: change the return type to boolean. The function name is left unchanged as it fits the naming expectation for a boolean. patch was compile tested for x86_64_defconfig (implies CONFIG_SRCU=y) patch is against 4.1-rc5 (localversion-next is -next-20150525) Signed-off-by: Nicholas Mc Guire Signed-off-by: Paul E. McKenney

rcu: Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()

2015-05-27T19:56:15Z

This commit moves from the old ACCESS_ONCE() API to the new READ_ONCE() and WRITE_ONCE() APIs. Signed-off-by: Paul E. McKenney [ paulmck: Updated to include kernel/torture.c as suggested by Jason Low. ]

Merge branches 'doc.2015.02.26a', 'earlycb.2015.03.03a', 'fixes.2015.03.03a', 'gpexp.2015.02.26a', 'hotplug.2015.03.20a', 'sysidle.2015.02.26b' and 'tiny.2015.02.26a' into HEAD

2015-03-20T15:31:01Z

doc.2015.02.26a: Documentation changes earlycb.2015.03.03a: Permit early-boot RCU callbacks fixes.2015.03.03a: Miscellaneous fixes gpexp.2015.02.26a: In-kernel expediting of normal grace periods hotplug.2015.03.20a: CPU hotplug fixes sysidle.2015.02.26b: NO_HZ_FULL_SYSIDLE fixes tiny.2015.02.26a: TINY_RCU fixes

rcu: Update from rcu_expedited variable to rcu_gp_is_expedited()

2015-02-26T20:03:01Z

This commit updates open-coded tests of the rcu_expedited variable to instead use rcu_gp_is_expedited(). Signed-off-by: Paul E. McKenney

rcu: Consolidate rcu_synchronize and wakeme_after_rcu()

2015-02-26T01:03:03Z

There are currently duplicate identical definitions of the rcu_synchronize() structure and the wakeme_after_rcu() function. Thie commit therefore consolidates them. Signed-off-by: Paul E. McKenney

rcu: Expand SRCU ->completed to 64 bits

2015-01-06T19:04:26Z

When rcutorture used only the low-order 32 bits of the grace-period number, it was not a problem for SRCU to use a 32-bit completed field. However, rcutorture now uses the full 64 bits on 64-bit systems, so this commit converts SRCU's ->completed field to unsigned long so as to provide 64 bits on 64-bit systems. Signed-off-by: Paul E. McKenney

rcu: Eliminate read-modify-write ACCESS_ONCE() calls

2014-07-09T16:14:49Z

RCU contains code of the following forms: ACCESS_ONCE(x)++; ACCESS_ONCE(x) += y; ACCESS_ONCE(x) -= y; Now these constructs do operate correctly, but they really result in a pair of volatile accesses, one to do the load and another to do the store. This can be confusing, as the casual reader might well assume that (for example) gcc might generate a memory-to-memory add instruction for each of these three cases. In fact, gcc will do no such thing. Also, there is a good chance that the kernel will move to separate load and store variants of ACCESS_ONCE(), and constructs like the above could easily confuse both people and scripts attempting to make that sort of change. Finally, most of RCU's read-modify-write uses of ACCESS_ONCE() really only need the store to be volatile, so that the read-modify-write form might be misleading. This commit therefore changes the above forms in RCU so that each instance of ACCESS_ONCE() either does a load or a store, but not both. In a few cases, ACCESS_ONCE() was not critical, for example, for maintaining statisitics. In these cases, ACCESS_ONCE() has been dispensed with entirely. Suggested-by: Linus Torvalds Signed-off-by: Paul E. McKenney