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From: Nick Lowe <nick.lowe@gmail.com>
To: "Nguyen, Anthony L" <anthony.l.nguyen@intel.com>
Cc: "kuba@kernel.org" <kuba@kernel.org>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"Siwik, Grzegorz" <grzegorz.siwik@intel.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"sassmann@redhat.com" <sassmann@redhat.com>,
	"Switzer, David" <david.switzer@intel.com>
Subject: Re: [PATCH net-next 2/6] igb: Add double-check MTA_REGISTER for i210 and i211
Date: Mon, 10 May 2021 14:43:55 +0100	[thread overview]
Message-ID: <CADSoG1uYJGygF9rm+15BE4gy=RU9EBbmGv_+pzddrKLJLdV14w@mail.gmail.com> (raw)
In-Reply-To: <b2850afee64efb6af2415cb3db75d4de14f3a1e2.camel@intel.com>

Hi all,

> > Looks like a potential infinite loop on persistent failure.
> > Also you don't need "is_failed", you can use while (i >= 0), or
> > assign i = hw->mac.mta_reg_count, or consider using a goto.
>
> We will make a follow on patch to address these issues.
>
> Thanks,
> Tony

The patch for this that has been queued is as follows:

+     int failed_cnt = 3;
+     bool is_failed;
+     int i;
+
+     do {
+          is_failed = false;
+          for (i = hw->mac.mta_reg_count - 1; i >= 0; i--) {
+               if (array_rd32(E1000_MTA, i) != hw->mac.mta_shadow[i]) {
+                    is_failed = true;
+                    array_wr32(E1000_MTA, i, hw->mac.mta_shadow[i]);
+                    wrfl();
+               }
+          }
+          if (is_failed && --failed_cnt <= 0) {
+               hw_dbg("Failed to update MTA_REGISTER, too many retries");
+               break;
+          }
+     } while (is_failed);

https://git.kernel.org/pub/scm/linux/kernel/git/tnguy/next-queue.git/commit/?h=dev-queue&id=9db33b54fb98525e323d0d3f16b01778f17b9493

This will not reset the counter when checking each register and it
will not debug output which register failed, this does not seem
optimal.

Could it make more sense to instead do something like this? (Untested)

+     int i;
+     int attempt;
+     for (i = hw->mac.mta_reg_count - 1; i >= 0; i--) {
+          for (attempt = 3; attempt >= 1; attempt--) {
+               if (array_rd32(E1000_MTA, i) != hw->mac.mta_shadow[i]) {
+                    array_wr32(E1000_MTA, i, hw->mac.mta_shadow[i]);
+                    wrfl();
+
+                    if (attempt == 1 && array_rd32(E1000_MTA, i) !=
hw->mac.mta_shadow[i]) {
+                         hw_dbg("Failed to update MTA_REGISTER %d,
too many retries\n", i);
+                    }
+               }
+          }
+     }

Best,

Nick

  reply	other threads:[~2021-05-10 14:08 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-16 20:44 [PATCH net-next 0/6][pull request] 1GbE Intel Wired LAN Driver Updates 2021-04-16 Tony Nguyen
2021-04-16 20:44 ` [PATCH net-next 1/6] igb: Redistribute memory for transmit packet buffers when in Qav mode Tony Nguyen
2021-04-16 20:44 ` [PATCH net-next 2/6] igb: Add double-check MTA_REGISTER for i210 and i211 Tony Nguyen
2021-04-16 21:12   ` Jakub Kicinski
2021-04-20 16:22     ` Nguyen, Anthony L
2021-05-10 13:43       ` Nick Lowe [this message]
2021-05-10 14:01         ` Nick Lowe
2021-05-13 12:19         ` Siwik, Grzegorz
2021-04-16 20:44 ` [PATCH net-next 3/6] igc: Enable internal i225 PPS Tony Nguyen
2021-04-16 20:44 ` [PATCH net-next 4/6] igc: enable auxiliary PHC functions for the i225 Tony Nguyen
2021-04-16 20:44 ` [PATCH net-next 5/6] igc: Fix overwrites return value Tony Nguyen
2021-04-16 20:45 ` [PATCH net-next 6/6] igc: Expose LPI counters Tony Nguyen
2021-04-17  0:20 ` [PATCH net-next 0/6][pull request] 1GbE Intel Wired LAN Driver Updates 2021-04-16 patchwork-bot+netdevbpf

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