Re: [PATCH net] bnx2x: don't reset chip on cleanup if PCI function is offline

On 08/10/2016 04:59 AM, Yuval Mintz wrote:

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Why would the published resume()  from pci_error_handlers be called in this

scenario?

It isn't. That's why I specifically commented on commit message: "There are two
cases though that another path is taken on the code".

The code path reach bnx2x_chip_cleanup() on device removal from the system,
as seen in the below call trace:

bnx2x_chip_cleanup+0x3c0/0x910 [bnx2x]
bnx2x_nic_unload+0x268/0xaf0 [bnx2x]
bnx2x_close+0x34/0x50 [bnx2x]
__dev_close_many+0xd4/0x150
dev_close_many+0xa8/0x160
rollback_registered_many+0x174/0x3f0
rollback_registered+0x40/0x70
unregister_netdevice_queue+0x98/0x110
unregister_netdev+0x34/0x50
__bnx2x_remove+0xa8/0x3a0 [bnx2x]
pci_device_remove+0x70/0x110

Makes sense.

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Also, we avoid the MCP information dump in case of non-recoverable
PCI error (when adapter is about to be removed), since it will certainly fail.

We should probably avoid several things here; Why specifically only this?

For example, we shouldn't execute bnx2x_timer() in this scenario. But I thought
it'd be too much to check every call of a timer function against PCI channel state
just to avoid it's execution on this scenario, so I just let it execute, since it seems
harmless.

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+	/* Reset the chip, unless PCI function is offline. If we reach this
+	 * point following a PCI error handling, it means device is really
+	 * in a bad state and we're about to remove it, so reset the chip
+	 * is not a good idea.
+	 */
+	if (!pci_channel_offline(bp->pdev)) {
+		rc = bnx2x_reset_hw(bp, reset_code);
+		if (rc)
+			BNX2X_ERR("HW_RESET failed\n");
+	}

Why not simply check this at the beginning of the function?

Because I wasn't sure if I could drop the entire execution of chip_cleanup(). I
tried to keep the most of this function aiming to shutdown the module in a
gentle way, like cleaning MAC, stopping queues...but again, I'm open to
suggestions and gladly will change this in v2 if you think it's for the best.

Problem is I won't be able to have a more thorough review of this in the next
couple of days - and other than code-review I won't have a reasonable way
of testing this [I can use aer_inject, but I don't have your magical EEH
error injections, and I'm not at all certain it would suffice for a good testing ].

I agree that even as-is, what you're suggesting is an improvement to the
existing flow - so it's basically up to dave, i.e., whether to take a half fix
or wait for a more thorough one.

Thanks for your consideration. The point is: the important part of this 
patch is avoiding the reset_hw() path, since it will clearly fail and 
generate soft lockups. This is the fix per se, the other part (regarding 
the MCP dump) is just an improvement; surely we have more potential 
improvements to explore, but they wouldn't be fixes, only code improvements.

So, I wouldn't call this a half fix, but yet, a completely fix with a 
small improvement as a bonus :)

Cheers,


Guilherme