netdev - Re: [PATCH v3 resubmit] fec: Restart PPS after link state change

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Message-ID: <20220905180542.GA3685102@roeck-us.net>
Date:   Mon, 5 Sep 2022 11:05:42 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Csókás Bence <csokas.bence@...lan.hu>
Cc:     netdev@...r.kernel.org, Richard Cochran <richardcochran@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, qiangqing.zhang@....com,
        Andrew Lunn <andrew@...n.ch>
Subject: Re: [PATCH v3 resubmit] fec: Restart PPS after link state change

On Mon, Aug 22, 2022 at 10:10:52AM +0200, Csókás Bence wrote:
> On link state change, the controller gets reset,
> causing PPS to drop out and the PHC to lose its
> time and calibration. So we restart it if needed,
> restoring calibration and time registers.
> 
> Changes since v2:
> * Add `fec_ptp_save_state()`/`fec_ptp_restore_state()`
> * Use `ktime_get_real_ns()`
> * Use `BIT()` macro
> Changes since v1:
> * More ECR #define's
> * Stop PPS in `fec_ptp_stop()`
> 
> Signed-off-by: Csókás Bence <csokas.bence@...lan.hu>

Besides the problem already reported (widespread BUG: sleeping function
called from invalid context at kernel/locking/mutex.c:580, called from
fec_ptp_gettime), this patch results in a crash when trying to boot the
m68k:mcf5208evb emulation in qemu. Reverting this patch fixes the problem.

Guenter

---
*** ILLEGAL INSTRUCTION ***   FORMAT=4
Current process id is 1
BAD KERNEL TRAP: 00000000
PC: [<00000000>] 0x0
SR: 2714  SP: (ptrval)  a2: 40829634
d0: 00002710    d1: 00002010    d2: 40829442    d3: 00002010
d4: 00000000    d5: 402e818a    a0: 00000000    a1: 40824000
Process swapper (pid: 1, task=(ptrval))
Frame format=4 eff addr=400681c2 pc=00000000
Stack from 40831cec:
        40829442 00002010 40831e0c 402e818a 40ba2000 00000008 408295a4 40829000
        401b0c42 40829634 40829420 00000000 40829420 40829000 00000000 00000001
        00000000 401b130e 408295a4 40829702 40347ee0 401ad026 40829420 40347eea
        00000000 40831e0c 402e818a 40ba2000 00000008 40347ee0 40829000 fffffff8
        4082945a 4082945a 40831e14 00000002 00000000 00000000 00000000 00000000
        00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
Call Trace: [<401b0c42>] fec_ptp_gettime+0x3a/0x8c
 [<401b130e>] fec_ptp_save_state+0x12/0x3e
 [<401ad026>] fec_restart+0x5a/0x770
 [<401ae256>] fec_probe+0x74a/0xd06
 [<402c10a0>] strcpy+0x0/0x18
 [<402d3824>] mutex_unlock+0x0/0x40
 [<402d37e4>] mutex_lock+0x0/0x40
 [<401840ba>] uart_get_icount+0x9c/0x198
 [<40193876>] platform_probe+0x22/0x60
 [<40191c52>] really_probe+0xb0/0x2e4
 [<40191f40>] driver_probe_device+0x24/0x112
 [<40192290>] __driver_attach+0x7a/0x200
 [<402b6458>] klist_next+0x0/0x154
 [<40192216>] __driver_attach+0x0/0x200
 [<4036cac2>] do_one_initcall+0x0/0x22c
 [<4019025c>] bus_for_each_dev+0x6a/0xae
 [<40192866>] driver_attach+0x16/0x1c
 [<40192216>] __driver_attach+0x0/0x200
 [<40190b5a>] bus_add_driver+0x154/0x222
 [<40192f9a>] driver_register+0x6c/0xf0
 [<40377d4a>] fec_driver_init+0x0/0x12
 [<40377d58>] fec_driver_init+0xe/0x12
 [<4036cb1e>] do_one_initcall+0x5c/0x22c
 [<402c10a0>] strcpy+0x0/0x18
 [<4036cac2>] do_one_initcall+0x0/0x22c
 [<402c10a0>] strcpy+0x0/0x18
 [<4036cac2>] do_one_initcall+0x0/0x22c
 [<4003d686>] parse_args+0x0/0x390
 [<4036ce8a>] kernel_init_freeable+0x144/0x1a4
 [<4003d686>] parse_args+0x0/0x390
 [<4036ce98>] kernel_init_freeable+0x152/0x1a4
 [<40377d4a>] fec_driver_init+0x0/0x12
 [<400977d6>] kfree+0x0/0x206
 [<402d2288>] schedule+0x0/0x120
 [<4003d686>] parse_args+0x0/0x390
 [<402cb5d0>] _printk+0x0/0x18
 [<402d0bb0>] kernel_init+0x0/0xf0
 [<402d0bca>] kernel_init+0x1a/0xf0
 [<400208d4>] ret_from_kernel_thread+0xc/0x14
Code: 0000 0000 0000 0000 0000 0000 0000 0000 <0000> 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
Disabling lock debugging due to kernel taint
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b