[PATCH v3 39/41] cxlflash: Synchronize reset and remove ops

[Matthew R. Ochs]

On Mon, Mar 26, 2018 at 11:35:27AM -0500, Uma Krishnan wrote:
> The following Oops can be encountered if a device removal or system
> shutdown is initiated while an EEH recovery is in process:
> 
> [c000000ff2f479c0] c008000015256f18 cxlflash_pci_slot_reset+0xa0/0x100
>                                       [cxlflash]
> [c000000ff2f47a30] c00800000dae22e0 cxl_pci_slot_reset+0x168/0x290 [cxl]
> [c000000ff2f47ae0] c00000000003ef1c eeh_report_reset+0xec/0x170
> [c000000ff2f47b20] c00000000003d0b8 eeh_pe_dev_traverse+0x98/0x170
> [c000000ff2f47bb0] c00000000003f80c eeh_handle_normal_event+0x56c/0x580
> [c000000ff2f47c60] c00000000003fba4 eeh_handle_event+0x2a4/0x338
> [c000000ff2f47d10] c0000000000400b8 eeh_event_handler+0x1f8/0x200
> [c000000ff2f47dc0] c00000000013da48 kthread+0x1a8/0x1b0
> [c000000ff2f47e30] c00000000000b528 ret_from_kernel_thread+0x5c/0xb4
> 
> The remove handler frees AFU memory while the EEH recovery is in progress,
> leading to a race condition. This can result in a crash if the recovery
> thread tries to access this memory.
> 
> To resolve this issue, the cxlflash remove handler will evaluate the
> device state and yield to any active reset or probing threads.
> 
> Signed-off-by: Uma Krishnan <ukrishn at linux.vnet.ibm.com>

Looks good!

Acked-by: Matthew R. Ochs <mrochs at linux.vnet.ibm.com>