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authorBen Hutchings <bhutchings@solarflare.com>2008-05-16 16:18:14 -0400
committerJeff Garzik <jgarzik@redhat.com>2008-05-22 05:59:29 -0400
commit5b9e207ced5bb7af98b3c147171893435f5104ca (patch)
tree3ddf00b344697899b608fbb4730e93f3621f22ce /drivers/net
parent086ea3564a5378a06c7cbfaf9d2727bc58a8c285 (diff)
sfc: Correct and expand some comments
These comments have been revised in response to questions raised by Andrew Morton in <20080501120858.207b6dd6.akpm@linux-foundation.org>. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/sfc/efx.c20
1 files changed, 14 insertions, 6 deletions
diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index f6131e578b44..11ee0d4407c4 100644
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -199,11 +199,12 @@ static inline int efx_process_channel(struct efx_channel *channel, int rx_quota)
199 */ 199 */
200static inline void efx_channel_processed(struct efx_channel *channel) 200static inline void efx_channel_processed(struct efx_channel *channel)
201{ 201{
202 /* Write to EVQ_RPTR_REG. If a new event arrived in a race 202 /* The interrupt handler for this channel may set work_pending
203 * with finishing processing, a new interrupt will be raised. 203 * as soon as we acknowledge the events we've seen. Make sure
204 */ 204 * it's cleared before then. */
205 channel->work_pending = 0; 205 channel->work_pending = 0;
206 smp_wmb(); /* Ensure channel updated before any new interrupt. */ 206 smp_wmb();
207
207 falcon_eventq_read_ack(channel); 208 falcon_eventq_read_ack(channel);
208} 209}
209 210
@@ -427,9 +428,12 @@ static void efx_start_channel(struct efx_channel *channel)
427 netif_napi_add(channel->napi_dev, &channel->napi_str, 428 netif_napi_add(channel->napi_dev, &channel->napi_str,
428 efx_poll, napi_weight); 429 efx_poll, napi_weight);
429 430
431 /* The interrupt handler for this channel may set work_pending
432 * as soon as we enable it. Make sure it's cleared before
433 * then. Similarly, make sure it sees the enabled flag set. */
430 channel->work_pending = 0; 434 channel->work_pending = 0;
431 channel->enabled = 1; 435 channel->enabled = 1;
432 smp_wmb(); /* ensure channel updated before first interrupt */ 436 smp_wmb();
433 437
434 napi_enable(&channel->napi_str); 438 napi_enable(&channel->napi_str);
435 439
@@ -1332,13 +1336,17 @@ static int efx_net_stop(struct net_device *net_dev)
1332 return 0; 1336 return 0;
1333} 1337}
1334 1338
1335/* Context: process, dev_base_lock held, non-blocking. */ 1339/* Context: process, dev_base_lock or RTNL held, non-blocking. */
1336static struct net_device_stats *efx_net_stats(struct net_device *net_dev) 1340static struct net_device_stats *efx_net_stats(struct net_device *net_dev)
1337{ 1341{
1338 struct efx_nic *efx = net_dev->priv; 1342 struct efx_nic *efx = net_dev->priv;
1339 struct efx_mac_stats *mac_stats = &efx->mac_stats; 1343 struct efx_mac_stats *mac_stats = &efx->mac_stats;
1340 struct net_device_stats *stats = &net_dev->stats; 1344 struct net_device_stats *stats = &net_dev->stats;
1341 1345
1346 /* Update stats if possible, but do not wait if another thread
1347 * is updating them (or resetting the NIC); slightly stale
1348 * stats are acceptable.
1349 */
1342 if (!spin_trylock(&efx->stats_lock)) 1350 if (!spin_trylock(&efx->stats_lock))
1343 return stats; 1351 return stats;
1344 if (efx->state == STATE_RUNNING) { 1352 if (efx->state == STATE_RUNNING) {