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be2net: fix a possible events_get() race on BE2

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On BE2 chip, an interrupt being raised even when EQ is in un-armed state has
been observed a few times.  This is not expected and has never been
observed on BE3/Lancer chips.

As a consequence, be_msix()::events_get() and be_poll()::events_get()
can race and notify an EQ wrongly causing a CEV UE. The other possible
side-effect would be traffic stalling because after notifying EQ,
napi_schedule() is ignored as NAPI is already running.

This patch fixes this issue by counting events only in be_poll().

Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sathya Perla 2012-11-23 00:27:18 +00:00 • committed by David S. Miller
commit 0b545a6291
1 changed files with 7 additions and 4 deletions
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11
drivers/net/ethernet/emulex/benet/be_main.c
View file

@ -2029,7 +2029,8 @@ static irqreturn_t be_msix(int irq, void *dev)
{
struct be_eq_obj *eqo = dev;
event_handle(eqo);
be_eq_notify(eqo->adapter, eqo->q.id, false, true, 0);
napi_schedule(&eqo->napi);
return IRQ_HANDLED;
}
@ -2125,9 +2126,11 @@ int be_poll(struct napi_struct *napi, int budget)
{
struct be_eq_obj *eqo = container_of(napi, struct be_eq_obj, napi);
struct be_adapter *adapter = eqo->adapter;
int max_work = 0, work, i;
int max_work = 0, work, i, num_evts;
bool tx_done;
num_evts = events_get(eqo);
/* Process all TXQs serviced by this EQ */
for (i = eqo->idx; i < adapter->num_tx_qs; i += adapter->num_evt_qs) {
tx_done = be_process_tx(adapter, &adapter->tx_obj[i],
@ -2150,10 +2153,10 @@ int be_poll(struct napi_struct *napi, int budget)
if (max_work < budget) {
napi_complete(napi);
be_eq_notify(adapter, eqo->q.id, true, false, 0);
be_eq_notify(adapter, eqo->q.id, true, false, num_evts);
} else {
/* As we'll continue in polling mode, count and clear events */
be_eq_notify(adapter, eqo->q.id, false, false, events_get(eqo));
be_eq_notify(adapter, eqo->q.id, false, false, num_evts);
}
return max_work;
}