diff options
| author | K. Y. Srinivasan <kys@microsoft.com> | 2016-01-28 09:29:44 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-02-08 08:34:12 +0300 |
| commit | 3eba9a77d5fc2cee486a16fff435686f024f61cf (patch) | |
| tree | de72dc9b5edc88f242121f589ad33d37f76f747e | |
| parent | 85d9aa705184a4504d0330017e3956fcdae8a9d6 (diff) | |
| download | linux-3eba9a77d5fc2cee486a16fff435686f024f61cf.tar.xz | |
Drivers: hv: vmbus: Eliminate the spin lock on the read path
The function hv_ringbuffer_read() is called always on a pre-assigned
CPU. Each chnnel is bound to a specific CPU and this function is
always called on the CPU the channel is bound. There is no need to
acquire the spin lock; get rid of this overhead.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/hv/ring_buffer.c | 18 |
1 files changed, 5 insertions, 13 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index b53702ce692f..1145f3b8e4e0 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -388,7 +388,6 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, u32 bytes_avail_toread; u32 next_read_location = 0; u64 prev_indices = 0; - unsigned long flags; struct vmpacket_descriptor desc; u32 offset; u32 packetlen; @@ -397,7 +396,6 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, if (buflen <= 0) return -EINVAL; - spin_lock_irqsave(&inring_info->ring_lock, flags); *buffer_actual_len = 0; *requestid = 0; @@ -412,7 +410,7 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, * No error is set when there is even no header, drivers are * supposed to analyze buffer_actual_len. */ - goto out_unlock; + return ret; } next_read_location = hv_get_next_read_location(inring_info); @@ -425,15 +423,11 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, *buffer_actual_len = packetlen; *requestid = desc.trans_id; - if (bytes_avail_toread < packetlen + offset) { - ret = -EAGAIN; - goto out_unlock; - } + if (bytes_avail_toread < packetlen + offset) + return -EAGAIN; - if (packetlen > buflen) { - ret = -ENOBUFS; - goto out_unlock; - } + if (packetlen > buflen) + return -ENOBUFS; next_read_location = hv_get_next_readlocation_withoffset(inring_info, offset); @@ -460,7 +454,5 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, *signal = hv_need_to_signal_on_read(bytes_avail_towrite, inring_info); -out_unlock: - spin_unlock_irqrestore(&inring_info->ring_lock, flags); return ret; } |