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net: Detect drivers that reschedule NAPI and exhaust budget 

The commit d75b1ade56 (net: less
interrupt masking in NAPI) required drivers to leave poll_list
empty if the entire budget is consumed.

We have already had two broken drivers so let's add a check for
this.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2014-12-21 07:16:22 +11:00 committed by David S. Miller
parent 726ce70e9e
commit 001ce546bb
1 changed files with 9 additions and 0 deletions
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net/core/dev.c
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@ -4602,6 +4602,15 @@ static int napi_poll(struct napi_struct *n, struct list_head *repoll)
napi_gro_flush(n, HZ >= 1000);
}
/* Some drivers may have called napi_schedule
* prior to exhausting their budget.
*/
if (unlikely(!list_empty(&n->poll_list))) {
pr_warn_once("%s: Budget exhausted after napi rescheduled\n",
n->dev ? n->dev->name : "backlog");
goto out_unlock;
}
list_add_tail(&n->poll_list, repoll);
out_unlock: