Bug 199716 - em doesn't increment adapter->rx_overruns in msix mode
Summary: em doesn't increment adapter->rx_overruns in msix mode
Status: Closed FIXED
Alias: None
Product: Base System
Classification: Unclassified
Component: kern (show other bugs)
Version: 10.1-STABLE
Hardware: Any Any
: --- Affects Many People
Assignee: freebsd-net (Nobody)
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2015-04-26 18:34 UTC by david.keller
Modified: 2015-05-25 00:30 UTC (History)
5 users (show)

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Description david.keller 2015-04-26 18:34:32 UTC 
When using msix interrupt model (e.g. 82574L chip), all interrupts excepted E1000_ICR_RXQ0, E1000_ICR_RXQ1, E1000_ICR_TXQ0, E1000_ICR_TXQ1 are handled by the em_msix_link() function.

Currently, this function only checks for E1000_ICR_LSC:
https://svnweb.freebsd.org/base/releng/10.1/sys/dev/e1000/if_em.c?view=markup#l1615

Hence when an E1000_ICR_RXO interrupt occurs, it's cleared (because of ICR reading), but adapter->rx_overruns is *not* incremented.

This may hide a chip hang (bug #199174).
Comment 1 Sean Bruno freebsd_committer freebsd_triage 2015-05-01 19:02:20 UTC 
I'm deep into the 82574L now.  I'll take this for review.
Comment 2 Sean Bruno freebsd_committer freebsd_triage 2015-05-01 19:25:44 UTC 
Index: if_em.c
===================================================================
--- if_em.c	(revision 282317)
+++ if_em.c	(working copy)
@@ -1609,6 +1609,9 @@
 	++adapter->link_irq;
 	reg_icr = E1000_READ_REG(&adapter->hw, E1000_ICR);
 
+	if (reg_icr & E1000_ICR_RXO)
+		adapter->rx_overruns++;
+
 	if (reg_icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC)) {
 		adapter->hw.mac.get_link_status = 1;
 		em_handle_link(adapter, 0);


Should DTRT
Comment 3 Hiren Panchasara freebsd_committer freebsd_triage 2015-05-01 20:04:37 UTC 
(In reply to Sean Bruno from comment #2)

I think so.

Also, nice catch, David. This *may* explain a behavior when we were setting a bunch of missed_packets on RX side with very less rx_overruns reported.
Comment 4 commit-hook freebsd_committer freebsd_triage 2015-05-22 17:02:26 UTC 
A commit references this bug:

Author: sbruno
Date: Fri May 22 17:01:44 UTC 2015
New revision: 283290
URL: https://svnweb.freebsd.org/changeset/base/283290

Log:
  Bump rx_overruns when indicated by the ICR mask.

  PR:		199716
  MFC after:	3 days
  Sponsored by:	Limelight Networks

Changes:
  head/sys/dev/e1000/if_em.c
Comment 5 commit-hook freebsd_committer freebsd_triage 2015-05-25 00:30:33 UTC 
A commit references this bug:

Author: sbruno
Date: Mon May 25 00:30:27 UTC 2015
New revision: 283504
URL: https://svnweb.freebsd.org/changeset/base/283504

Log:
  MFC r283290

  Bump rx_overruns when indicated by the ICR mask.

  PR:		199716
  Sponsored by:	Limelight Networks

Changes:
_U  stable/10/
  stable/10/sys/dev/e1000/if_em.c