diff options
| author | Ben Hutchings <bhutchings@solarflare.com> | 2008-05-16 22:18:14 +0200 |
|---|---|---|
| committer | Jeff Garzik <jgarzik@redhat.com> | 2008-05-22 11:59:29 +0200 |
| commit | 5b9e207ced5bb7af98b3c147171893435f5104ca (patch) | |
| tree | 3ddf00b344697899b608fbb4730e93f3621f22ce /drivers/net | |
| parent | sfc: Use resource_size_t for PCI bus address (diff) | |
| download | linux-5b9e207ced5bb7af98b3c147171893435f5104ca.tar.xz linux-5b9e207ced5bb7af98b3c147171893435f5104ca.zip | |
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.c | 20 |
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) */ static inline void efx_channel_processed(struct efx_channel *channel) { - /* Write to EVQ_RPTR_REG. If a new event arrived in a race - * with finishing processing, a new interrupt will be raised. - */ + /* The interrupt handler for this channel may set work_pending + * as soon as we acknowledge the events we've seen. Make sure + * it's cleared before then. */ channel->work_pending = 0; - smp_wmb(); /* Ensure channel updated before any new interrupt. */ + smp_wmb(); + falcon_eventq_read_ack(channel); } @@ -427,9 +428,12 @@ static void efx_start_channel(struct efx_channel *channel) netif_napi_add(channel->napi_dev, &channel->napi_str, efx_poll, napi_weight); + /* The interrupt handler for this channel may set work_pending + * as soon as we enable it. Make sure it's cleared before + * then. Similarly, make sure it sees the enabled flag set. */ channel->work_pending = 0; channel->enabled = 1; - smp_wmb(); /* ensure channel updated before first interrupt */ + smp_wmb(); napi_enable(&channel->napi_str); @@ -1332,13 +1336,17 @@ static int efx_net_stop(struct net_device *net_dev) return 0; } -/* Context: process, dev_base_lock held, non-blocking. */ +/* Context: process, dev_base_lock or RTNL held, non-blocking. */ static struct net_device_stats *efx_net_stats(struct net_device *net_dev) { struct efx_nic *efx = net_dev->priv; struct efx_mac_stats *mac_stats = &efx->mac_stats; struct net_device_stats *stats = &net_dev->stats; + /* Update stats if possible, but do not wait if another thread + * is updating them (or resetting the NIC); slightly stale + * stats are acceptable. + */ if (!spin_trylock(&efx->stats_lock)) return stats; if (efx->state == STATE_RUNNING) { |