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author | Jan Beulich <jbeulich@suse.com> | 2012-03-23 16:13:29 +0100 |
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committer | Jan Beulich <jbeulich@suse.com> | 2012-03-23 16:13:29 +0100 |
commit | 0f049e6e2b4919250b1c66fabdbf8d812aa43880 (patch) | |
tree | d792ba4075f0a3b0d4a4374ba15c52e7afde4f0d /xen/arch/x86/hpet.c | |
parent | e02af69dc20d4a9319fb6992be3d5bc3e41b49ab (diff) | |
download | xen-0f049e6e2b4919250b1c66fabdbf8d812aa43880.tar.gz xen-0f049e6e2b4919250b1c66fabdbf8d812aa43880.tar.bz2 xen-0f049e6e2b4919250b1c66fabdbf8d812aa43880.zip |
x86/hpet: simplify hpet_get_channel()
There's no need for a lock here, elimination of which makes the
function a leaf one, thus allowing for better (and smaller) code.
Further, use the variable next_channel according to its name - so far
it represented the most recently used channel rather than the next one
to use.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>
Diffstat (limited to 'xen/arch/x86/hpet.c')
-rw-r--r-- | xen/arch/x86/hpet.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/xen/arch/x86/hpet.c b/xen/arch/x86/hpet.c index b17cd07497..8ead34be60 100644 --- a/xen/arch/x86/hpet.c +++ b/xen/arch/x86/hpet.c @@ -402,16 +402,17 @@ static void __init hpet_fsb_cap_lookup(void) static struct hpet_event_channel *hpet_get_channel(unsigned int cpu) { static unsigned int next_channel; - static spinlock_t next_lock = SPIN_LOCK_UNLOCKED; unsigned int i, next; struct hpet_event_channel *ch; if ( num_hpets_used == 0 ) return hpet_events; - spin_lock(&next_lock); - next = next_channel = (next_channel + 1) % num_hpets_used; - spin_unlock(&next_lock); + do { + next = next_channel; + if ( (i = next + 1) == num_hpets_used ) + i = 0; + } while ( cmpxchg(&next_channel, next, i) != next ); /* try unused channel first */ for ( i = next; i < next + num_hpets_used; i++ ) |