Re: [PATCH v2 0/3] net: phy: leds: Fix truncated LED trigger names and crashes

[David Miller <davem@davemloft.net>]

From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Wed, 25 Jan 2017 11:39:47 +0100

> I started seeing crashes during s2ram and poweroff on all my ARM boards,
> like:
> 
>     Unable to handle kernel NULL pointer dereference at virtual address 00000000
>     ...
>     [<c04116d4>] (__list_del_entry_valid) from [<c05e8948>] (led_trigger_unregister+0x34/0xcc)
>     [<c05e8948>] (led_trigger_unregister) from [<c05336c4>] (phy_led_triggers_unregister+0x28/0x34)
>     [<c05336c4>] (phy_led_triggers_unregister) from [<c0531d44>] (phy_detach+0x30/0x74)
>     [<c0531d44>] (phy_detach) from [<c0538bdc>] (sh_eth_close+0x64/0x9c)
>     [<c0538bdc>] (sh_eth_close) from [<c04d4ce0>] (dpm_run_callback+0x48/0xc8)
> 
> or:
> 
>     list_del corruption. prev->next should be dede6540, but was 2e323931
>     ------------[ cut here ]------------
>     kernel BUG at lib/list_debug.c:52!
>     ...
>     [<c02f6d70>] (__list_del_entry_valid) from [<c0425168>] (led_trigger_unregister+0x34/0xcc)
>     [<c0425168>] (led_trigger_unregister) from [<c03a05a0>] (phy_led_triggers_unregister+0x28/0x34)
>     [<c03a05a0>] (phy_led_triggers_unregister) from [<c039ec04>] (phy_detach+0x30/0x74)
>     [<c039ec04>] (phy_detach) from [<c03a4fc0>] (sh_eth_close+0x6c/0xa4)
>     [<c03a4fc0>] (sh_eth_close) from [<c0483234>] (__dev_close_many+0xac/0xd0)
> 
> As the only clue was a kernel message like
> 
>     sh-eth ee700000.ethernet eth0: No phy led trigger registered for speed(100)
> 
> I had to bisected this, leading to commit 4567d686f5c6d955 ("phy:
> increase size of MII_BUS_ID_SIZE and bus_id").  Reverting that commit
> fixed the issue.
> 
> More investigation revealed the crashes are due to the combination of
> two things:
>   - Truncated LED trigger names, leading to duplicate names, and
>     registration failures,
>   - Bad error handling in case of registration failures.
> 
> Both are fixed by this patch series.

Thanks for tracking this down and fixing it.

Series applied, thanks.