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authorDaniel Vetter <daniel.vetter@ffwll.ch>2012-05-07 13:30:46 +0400
committerDaniel Vetter <daniel.vetter@ffwll.ch>2012-05-07 16:02:14 +0400
commitdc257cf154be708ecc47b8b89c12ad8cd2cc35e4 (patch)
tree625d57ef6c42030cc1ce1842d4efc105e284bc3d /include/linux/seqlock.h
parent5bc69bf9aeb73547cad8e1ce683a103fe9728282 (diff)
parentd48b97b403d23f6df0b990cee652bdf9a52337a3 (diff)
downloadlinux-dc257cf154be708ecc47b8b89c12ad8cd2cc35e4.tar.xz
Merge tag 'v3.4-rc6' into drm-intel-next
Conflicts: drivers/gpu/drm/i915/intel_display.c Ok, this is a fun story of git totally messing things up. There /shouldn't/ be any conflict in here, because the fixes in -rc6 do only touch functions that have not been changed in -next. The offending commits in drm-next are 14415745b2..1fa611065 which simply move a few functions from intel_display.c to intel_pm.c. The problem seems to be that git diff gets completely confused: $ git diff 14415745b2..1fa611065 is a nice mess in intel_display.c, and the diff leaks into totally unrelated functions, whereas $git diff --minimal 14415745b2..1fa611065 is exactly what we want. Unfortunately there seems to be no way to teach similar smarts to the merge diff and conflict generation code, because with the minimal diff there really shouldn't be any conflicts. For added hilarity, every time something in that area changes the + and - lines in the diff move around like crazy, again resulting in new conflicts. So I fear this mess will stay with us for a little longer (and might result in another backmerge down the road). Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'include/linux/seqlock.h')
-rw-r--r--include/linux/seqlock.h23
1 files changed, 22 insertions, 1 deletions
diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
index c6db9fb33c44..600060e25ec6 100644
--- a/include/linux/seqlock.h
+++ b/include/linux/seqlock.h
@@ -141,7 +141,7 @@ static inline unsigned __read_seqcount_begin(const seqcount_t *s)
unsigned ret;
repeat:
- ret = s->sequence;
+ ret = ACCESS_ONCE(s->sequence);
if (unlikely(ret & 1)) {
cpu_relax();
goto repeat;
@@ -166,6 +166,27 @@ static inline unsigned read_seqcount_begin(const seqcount_t *s)
}
/**
+ * raw_seqcount_begin - begin a seq-read critical section
+ * @s: pointer to seqcount_t
+ * Returns: count to be passed to read_seqcount_retry
+ *
+ * raw_seqcount_begin opens a read critical section of the given seqcount.
+ * Validity of the critical section is tested by checking read_seqcount_retry
+ * function.
+ *
+ * Unlike read_seqcount_begin(), this function will not wait for the count
+ * to stabilize. If a writer is active when we begin, we will fail the
+ * read_seqcount_retry() instead of stabilizing at the beginning of the
+ * critical section.
+ */
+static inline unsigned raw_seqcount_begin(const seqcount_t *s)
+{
+ unsigned ret = ACCESS_ONCE(s->sequence);
+ smp_rmb();
+ return ret & ~1;
+}
+
+/**
* __read_seqcount_retry - end a seq-read critical section (without barrier)
* @s: pointer to seqcount_t
* @start: count, from read_seqcount_begin