From: David S. Miller <davem@davemloft.net>
Date: Wed, 25 Jan 2017 19:40:25 +0000 (-0500)
Subject: Merge branch 'phy-truncated-led-names'
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=d5bdc021ecc8b273259a02ff83ab13b2de9b9717;p=linux-beck.git

Merge branch 'phy-truncated-led-names'

Geert Uytterhoeven says:

====================
net: phy: leds: Fix truncated LED trigger names and crashes

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.

Changes compared to v1:
  - Add Reviewed-by,
  - New patch "net: phy: leds: Break dependency of phy.h on
    phy_led_triggers.h",
  - Drop moving the include of <linux/phy_led_triggers.h>, as
    <linux/phy.h> no longer includes it,
  - #include <linux/phy.h> from <linux/phy_led_triggers.h>.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
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d5bdc021ecc8b273259a02ff83ab13b2de9b9717