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author | Peter Zijlstra <peterz@infradead.org> | 2018-03-15 11:40:33 +0100 |
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committer | Ingo Molnar <mingo@kernel.org> | 2018-03-20 08:23:17 +0100 |
commit | 6b2bb7265f0b62605e8caee3613449ed0db270b9 (patch) | |
tree | 62780e9b912f05daccd56f1bab31b0c280bb4043 /Kconfig | |
parent | fc4c5a3828bdba157f8ea406e1f4ceb75c13039c (diff) | |
download | linux-stable-6b2bb7265f0b62605e8caee3613449ed0db270b9.tar.gz linux-stable-6b2bb7265f0b62605e8caee3613449ed0db270b9.tar.bz2 linux-stable-6b2bb7265f0b62605e8caee3613449ed0db270b9.zip |
sched/wait: Introduce wait_var_event()
As a replacement for the wait_on_atomic_t() API provide the
wait_var_event() API.
The wait_var_event() API is based on the very same hashed-waitqueue
idea, but doesn't care about the type (atomic_t) or the specific
condition (atomic_read() == 0). IOW. it's much more widely
applicable/flexible.
It shares all the benefits/disadvantages of a hashed-waitqueue
approach with the existing wait_on_atomic_t/wait_on_bit() APIs.
The API is modeled after the existing wait_event() API, but instead of
taking a wait_queue_head, it takes an address. This addresses is
hashed to obtain a wait_queue_head from the bit_wait_table.
Similar to the wait_event() API, it takes a condition expression as
second argument and will wait until this expression becomes true.
The following are (mostly) identical replacements:
wait_on_atomic_t(&my_atomic, atomic_t_wait, TASK_UNINTERRUPTIBLE);
wake_up_atomic_t(&my_atomic);
wait_var_event(&my_atomic, !atomic_read(&my_atomic));
wake_up_var(&my_atomic);
The only difference is that wake_up_var() is an unconditional wakeup
and doesn't check the previously hard-coded (atomic_read() == 0)
condition here. This is of little concequence, since most callers are
already conditional on atomic_dec_and_test() and the ones that are
not, are trivial to make so.
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Kconfig')
0 files changed, 0 insertions, 0 deletions