Re: [PATCH 1/3] cxlflash: Fix to drain operations from previous reset

On Jun 15, 2016, at 6:49 PM, Uma Krishnan [off-list ref] =

wrote:

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From: "Manoj N. Kumar" <redacted>
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While running 'sg_reset -H' in a loop with a user-space application =

active,

hit the following exception:
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cpu 0x2: Vector: 300 (Data Access)
   pc: : afu_attach+0x50/0x240 [cxlflash]
   lr: : cxlflash_afu_recover+0x3dc/0x7d0 [cxlflash]
   pid   =3D 20365, comm =3D run_block_fvt
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Linux version 4.5.0-491-26f710d+
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cxlflash_afu_recover+0x3dc/0x7d0 [cxlflash]
cxlflash_ioctl+0x5a8/0x6f0 [cxlflash]
scsi_ioctl+0x3b0/0x4c0
sd_ioctl+0x110/0x190
blkdev_ioctl+0x28c/0xc20
block_ioctl+0xa4/0xd0
do_vfs_ioctl+0xd8/0x8c0
SyS_ioctl+0xd4/0xf0
system_call+0x38/0xb4
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The problem here is that the problem space area is unmapped while the
application issues the DK_CXLFLASH_RECOVER_AFU ioctl.
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This is the order I observe:
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proc1				proc2
1) sg_reset
				2) ioctl(DK_CXLFLASH_RECOVER_AFU)
3) sg_reset again
  causing a PSA unmap
				4) continues RECOVER_AFU processing
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The resolution to this problem is to have the reset handler drain all
outstanding user space initiated ioctls before proceeding.  It is safe
to drain after the state has been changed to STATE_RESET. Also since
drain_ioctls() was static, it had to be moved up a bit to be before
cxlflash_eh_host_reset_handler().
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Signed-off-by: Manoj N. Kumar <redacted>

Acked-by: Matthew R. Ochs <redacted>