Commit ee873fda3b
"gianfar: Pack struct gfar_priv_grp into three cachelines"
causes the following null dereference at driver init on sbc8548:
libphy: Freescale PowerQUICC MII Bus: probed
Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc01d6a38
Oops: Kernel access of bad area, sig: 11 [#1]
[...]
NIP [c01d6a38] gfar_parse_group+0x228/0x280
LR [c01d6a34] gfar_parse_group+0x224/0x280
Call Trace:
[ef82dd60] [c01d6a34] gfar_parse_group+0x224/0x280 (unreliable)
[ef82dd90] [c01d73a4] gfar_probe+0x284/0xfe0
The reason is that the commit also changed the allocation of the
Rx and error handling irq structs to be skipped for !MQ_MG_MODE.
In the !MQ_MG_MODE case, only the Tx irq struct is allocated.
Digging further, we see that MQ_MG_MODE is set only if we find
the OF compatible string "fsl,etsec2".
A quick grep in the dts directory shows lots of boards that support
Rx/Tx/Err, but without this specific compat string. And hence they
go after the unallocated Rx/Error structs and cause the above oops.
Hence such a change can not be deployed until all the dts files
are updated and sufficiently deployed. Further, the optimization
is of limited value, since the kmalloc'd struct in question has only
a single unsigned int, and an (IFNAMSIZ + 6) sized string.
Note that no changes to the freeing code are needed here, as it
already did an unconditional free of Rx/Tx/Error gfar_irqinfo.
Cc: Claudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
7c1e7e99ab