Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1366126

[tip:core/urgent] locking/atomic: Introduce atomic_fetch_or()

Show all headers | View raw

Commit-ID:  5acba71e18833b9d06686b3751598bfa263a3ac3
Gitweb:     http://git.kernel.org/tip/5acba71e18833b9d06686b3751598bfa263a3ac3
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Thu, 24 Mar 2016 15:37:59 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 29 Mar 2016 11:52:11 +0200

locking/atomic: Introduce atomic_fetch_or()

This is deemed to replace the type generic fetch_or() which brings a lot
of issues such as macro induced block variable aliasing and sloppy types.
Not to mention fetch_or() doesn't refer to any namespace, adding even
more confusion.

So lets provide an atomic_t version. Current and next users of fetch_or()
are thus encouraged to use atomic_t.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1458830281-4255-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 include/linux/atomic.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index df4f369..3d64c08 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -559,6 +559,27 @@ static inline int atomic_dec_if_positive(atomic_t *v)
 #endif
 
 /**
+ * atomic_fetch_or - perform *p |= mask and return old value of *p
+ * @p: pointer to atomic_t
+ * @mask: mask to OR on the atomic_t
+ */
+#ifndef atomic_fetch_or
+static inline int atomic_fetch_or(atomic_t *p, int mask)
+{
+	int old, val = atomic_read(p);
+
+	for (;;) {
+		old = atomic_cmpxchg(p, val, val | mask);
+		if (old == val)
+			break;
+		val = old;
+	}
+
+	return old;
+}
+#endif
+
+/**
  * fetch_or - perform *ptr |= mask and return old value of *ptr
  * @ptr: pointer to value
  * @mask: mask to OR on the value

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Frederic Weisbecker <fweisbec@gmail.com> - 2016-03-24 15:40 +0100
  [PATCH 1/3] atomic: Introduce atomic_fetch_or Frederic Weisbecker <fweisbec@gmail.com> - 2016-03-24 15:50 +0100
    [tip:core/urgent] locking/atomic: Introduce atomic_fetch_or() tip-bot for Frederic Weisbecker <tipbot@zytor.com> - 2016-03-29 12:40 +0200
  Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Ingo Molnar <mingo@kernel.org> - 2016-03-25 09:50 +0100
    Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Frederic Weisbecker <fweisbec@gmail.com> - 2016-03-25 14:20 +0100
      Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Ingo Molnar <mingo@kernel.org> - 2016-03-29 11:50 +0200
        Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Linus Torvalds <torvalds@linux-foundation.org> - 2016-03-29 14:30 +0200
          Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Frederic Weisbecker <fweisbec@gmail.com> - 2016-03-29 15:10 +0200
            Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Ingo Molnar <mingo@kernel.org> - 2016-03-31 09:00 +0200
              Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Peter Zijlstra <peterz@infradead.org> - 2016-03-31 11:30 +0200
                Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Ingo Molnar <mingo@kernel.org> - 2016-03-31 15:20 +0200
          Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Ingo Molnar <mingo@kernel.org> - 2016-03-29 15:10 +0200
            Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Ingo Molnar <mingo@kernel.org> - 2016-03-29 15:10 +0200
              Re: [PATCH 0/3] nohz: Convert tick dependency mask to atomic_t Ingo Molnar <mingo@kernel.org> - 2016-03-29 15:20 +0200

csiph-web