Re: [PATCH] iwlwifi: don't panic in error path on non-msix systems

[Kirtika Ruchandani]

On Mon, Apr 22, 2019 at 11:07 AM Michal Hocko <mhocko@xxxxxxxxxx> wrote:
>
> On Wed 17-04-19 10:35:16, Luca Coelho wrote:
> > From: Shahar S Matityahu <shahar.s.matityahu@xxxxxxxxx>
> >
> > The driver uses msix causes-register to handle both msix and non msix
> > interrupts when performing sync nmi.  On devices that do not support
> > msix this register is unmapped and accessing it causes a kernel panic.
> >
> > Solve this by differentiating the two cases and accessing the proper
> > causes-register in each case.

Are you sure reading CSR_INT from trans.c without explicitly getting irq_lock.c
like rx.c does, is thread-safe? I don't claim to understand this fully, but this
smells wrong from past experience with this driver. I'll see if I can cook up
a test case with a race condition here.

> >
> > Reported-by: Michal Hocko <mhocko@xxxxxxxxxx>
> > Signed-off-by: Shahar S Matityahu <shahar.s.matityahu@xxxxxxxxx>
> > Signed-off-by: Luca Coelho <luciano.coelho@xxxxxxxxx>
>
> $ dmesg | grep "Error sending SCAN_CFG_CMD:"
> [49786.288548] iwlwifi 0000:01:00.0: Error sending SCAN_CFG_CMD: time out after 2000ms.
> [53457.166877] iwlwifi 0000:01:00.0: Error sending SCAN_CFG_CMD: time out after 2000ms.
>
> without the oops and with the iwlwifi internal dump IIUC which is the
> previous behavior.
> [53457.166877] iwlwifi 0000:01:00.0: Error sending SCAN_CFG_CMD: time out after 2000ms.
> [53457.166882] iwlwifi 0000:01:00.0: Current CMD queue read_ptr 224 write_ptr 225
> [53457.414973] iwlwifi 0000:01:00.0: HW error, resetting before reading
> [53457.421339] iwlwifi 0000:01:00.0: Start IWL Error Log Dump:
> [53457.421345] iwlwifi 0000:01:00.0: Status: 0x00000100, count: 1269232956
> [53457.421347] iwlwifi 0000:01:00.0: Loaded firmware version: 36.9f0a2d68.0
> [53457.421350] iwlwifi 0000:01:00.0: 0x45E91306 | ADVANCED_SYSASSERT
> [53457.421352] iwlwifi 0000:01:00.0: 0x2F58D384 | trm_hw_status0
> [53457.421353] iwlwifi 0000:01:00.0: 0x7F1A8CFD | trm_hw_status1
> [53457.421355] iwlwifi 0000:01:00.0: 0x07E787FD | branchlink2
> [53457.421357] iwlwifi 0000:01:00.0: 0xE9E54368 | interruptlink1
> [53457.421359] iwlwifi 0000:01:00.0: 0x470D9BBF | interruptlink2
> [53457.421361] iwlwifi 0000:01:00.0: 0xAF040E7E | data1
> [53457.421362] iwlwifi 0000:01:00.0: 0xE7FBCA48 | data2
> [53457.421364] iwlwifi 0000:01:00.0: 0x4E4A8288 | data3
> [53457.421366] iwlwifi 0000:01:00.0: 0x861DEA98 | beacon time
> [53457.421368] iwlwifi 0000:01:00.0: 0xE8F23466 | tsf low
> [53457.421369] iwlwifi 0000:01:00.0: 0xD7B19307 | tsf hi
> [53457.421371] iwlwifi 0000:01:00.0: 0xE58934E3 | time gp1
> [53457.421373] iwlwifi 0000:01:00.0: 0xB013FEBE | time gp2
> [53457.421375] iwlwifi 0000:01:00.0: 0x962DCC75 | uCode revision type
> [53457.421376] iwlwifi 0000:01:00.0: 0xFF8FB30F | uCode version major
> [53457.421378] iwlwifi 0000:01:00.0: 0x0DD08E17 | uCode version minor
> [53457.421380] iwlwifi 0000:01:00.0: 0x87FD70DE | hw version
> [53457.421382] iwlwifi 0000:01:00.0: 0x853F6851 | board version
> [53457.421384] iwlwifi 0000:01:00.0: 0x08D7F330 | hcmd
> [53457.421385] iwlwifi 0000:01:00.0: 0x6B7E5FEE | isr0
> [53457.421387] iwlwifi 0000:01:00.0: 0x2B1E7CD4 | isr1
> [53457.421389] iwlwifi 0000:01:00.0: 0x3F133B16 | isr2
> [53457.421391] iwlwifi 0000:01:00.0: 0x5D480C5A | isr3
> [53457.421392] iwlwifi 0000:01:00.0: 0x34E93EBA | isr4
> [53457.421394] iwlwifi 0000:01:00.0: 0x42AD8E83 | last cmd Id
> [53457.421396] iwlwifi 0000:01:00.0: 0x1F5BBCFF | wait_event
> [53457.421398] iwlwifi 0000:01:00.0: 0x6808B2C1 | l2p_control
> [53457.421399] iwlwifi 0000:01:00.0: 0x0D5B1F33 | l2p_duration
> [53457.421401] iwlwifi 0000:01:00.0: 0xF4C94535 | l2p_mhvalid
> [53457.421403] iwlwifi 0000:01:00.0: 0x3DCE6EBB | l2p_addr_match
> [53457.421405] iwlwifi 0000:01:00.0: 0xFDDC41FE | lmpm_pmg_sel
> [53457.421406] iwlwifi 0000:01:00.0: 0xB53A17F5 | timestamp
> [53457.421408] iwlwifi 0000:01:00.0: 0x5A6A4113 | flow_handler
> [53457.421474] iwlwifi 0000:01:00.0: Start IWL Error Log Dump:
> [53457.421477] iwlwifi 0000:01:00.0: Status: 0x00000100, count: 1182976748
> [53457.421478] iwlwifi 0000:01:00.0: 0x62D2BDB3 | ADVANCED_SYSASSERT
> [53457.421480] iwlwifi 0000:01:00.0: 0x4D9E5019 | umac branchlink1
> [53457.421482] iwlwifi 0000:01:00.0: 0x8CB69F6E | umac branchlink2
> [53457.421484] iwlwifi 0000:01:00.0: 0x9868662D | umac interruptlink1
> [53457.421486] iwlwifi 0000:01:00.0: 0x9800F8F7 | umac interruptlink2
> [53457.421488] iwlwifi 0000:01:00.0: 0xC71449B8 | umac data1
> [53457.421489] iwlwifi 0000:01:00.0: 0xAB0AB17F | umac data2
> [53457.421491] iwlwifi 0000:01:00.0: 0x6C6F9753 | umac data3
> [53457.421493] iwlwifi 0000:01:00.0: 0xFC49D724 | umac major
> [53457.421495] iwlwifi 0000:01:00.0: 0xA61CC627 | umac minor
> [53457.421496] iwlwifi 0000:01:00.0: 0x45BAA0B8 | frame pointer
> [53457.421498] iwlwifi 0000:01:00.0: 0x319D112B | stack pointer
> [53457.421500] iwlwifi 0000:01:00.0: 0xEFD9E2E9 | last host cmd
> [53457.421502] iwlwifi 0000:01:00.0: 0x82640FF7 | isr status reg
> [53457.421506] ieee80211 phy0: Hardware restart was requested
> [53457.941685] iwlwifi 0000:01:00.0: Queue 0 is inactive on fifo 0 and stuck for 2500 ms. SW [224, 225] HW [0, 0] FH TRB=0x02b759ca1
>
> Feel free to add
> Tested-by: Michal Hocko <mhocko@xxxxxxxx>
>
> Thanks for your quick patch and sorry it took so long from my side.
>
> --
> Michal Hocko
> SUSE Labs