Re: [dpdk-dev] [PATCH v2] igb_uio: remove device reset in release

[Thomas Monjalon <thomas@monjalon.net>]

07/11/2017 23:29, Ferruh Yigit:
> More error reported for device reset in release() [1],
> when device pass-through to the guest, host kernel crash on guest exit.
> 
> Removing the reset completely.
> 
> This is close to reverting commit b58eedfc7dd5 [2], taking into account
> previous fix to remove reset in open as well [3], but not exactly same.
> 
> With latest code, interrupts are enabled in uio open() callback and
> disabled in uio release() callback, so when a DPDK application exit
> device interrupts are disabled. Previously interrupts were only enabled
> once in igb_uio module insert and disabled in module removal.
> 
> Also with latest code device set as bus master in open() and master
> cleared in release(), clearing bus master should prevent further DMA
> which was one of the target of the initial patch.
> 
> The initial intention was also to reset the device to be sure it has
> been left in proper state, but currently that part is missing because of
> reported problem(s).
> 
> Still igb_uio should be safer comparing to the pre b58eedfc7dd5 state.
> 
> [1]
> http://dpdk.org/ml/archives/dev/2017-November/081459.html
> 
> [2]
> b58eedfc7dd5 ("igb_uio: issue FLR during open and release of device file")
> 
> [3]
> f73b38e9245d ("igb_uio: remove device reset in open")
> 
> Fixes: e3a64deae2d5 ("igb_uio: prevent reset for bnx2x devices")
> Fixes: b58eedfc7dd5 ("igb_uio: issue FLR during open and release of device file")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>

We can say you tried hard to make igb_uio cleaner and safer :)

Applied, thanks for the detailed explanations.