9bba5955ee
[ Upstream commit a699781c79ecf6cfe67fb00a0331b4088c7c8466 ]
A sysfs reader can race with a device reset or removal, attempting to
read device state when the device is not actually present. eg:
[exception RIP: qed_get_current_link+17]
#8 [ffffb9e4f2907c48] qede_get_link_ksettings at ffffffffc07a994a [qede]
#9 [ffffb9e4f2907cd8] __rh_call_get_link_ksettings at ffffffff992b01a3
#10 [ffffb9e4f2907d38] __ethtool_get_link_ksettings at ffffffff992b04e4
#11 [ffffb9e4f2907d90] duplex_show at ffffffff99260300
#12 [ffffb9e4f2907e38] dev_attr_show at ffffffff9905a01c
#13 [ffffb9e4f2907e50] sysfs_kf_seq_show at ffffffff98e0145b
#14 [ffffb9e4f2907e68] seq_read at ffffffff98d902e3
#15 [ffffb9e4f2907ec8] vfs_read at ffffffff98d657d1
#16 [ffffb9e4f2907f00] ksys_read at ffffffff98d65c3f
#17 [ffffb9e4f2907f38] do_syscall_64 at ffffffff98a052fb
crash> struct net_device.state ffff9a9d21336000
state = 5,
state 5 is __LINK_STATE_START (0b1) and __LINK_STATE_NOCARRIER (0b100).
The device is not present, note lack of __LINK_STATE_PRESENT (0b10).
This is the same sort of panic as observed in commit
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| .. | ||
| bitset.c | ||
| bitset.h | ||
| cabletest.c | ||
| channels.c | ||
| coalesce.c | ||
| common.c | ||
| common.h | ||
| debug.c | ||
| eee.c | ||
| eeprom.c | ||
| features.c | ||
| fec.c | ||
| ioctl.c | ||
| linkinfo.c | ||
| linkmodes.c | ||
| linkstate.c | ||
| Makefile | ||
| module.c | ||
| netlink.c | ||
| netlink.h | ||
| pause.c | ||
| phc_vclocks.c | ||
| privflags.c | ||
| pse-pd.c | ||
| rings.c | ||
| stats.c | ||
| strset.c | ||
| tsinfo.c | ||
| tunnels.c | ||
| wol.c | ||