Re: [PATCH] iwlwifi: pcie: don't panic on host commands in iwldvm

[Kalle Valo <kvalo@adurom.com>]

Emmanuel Grumbach <egrumbach@gmail.com> writes:

> From: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
>
> None of the devices supported by iwldvm have support for
> shadow registers. This means that we wake the NIC
> when we increment the write pointer on Tx ring.
> This happened even before my bad commit mentionned below.
> Since my commit below, we wake up the NIC when we put a
> host command on the ring regardless of shadow register
> support. This means that in iwldvm (when the NIC doesn't
> support shadow register), we wake up the NIC twice:
>
> pcie_enqueue_hcmd:
> 	wake up the NIC
> 	iwl_pcie_txq_inc_wr_ptr:
> 		wake up the NIC - no shadow reg support
>
> Since waking up the NIC means that we need to acquire a
> spinlock, this obviously leads to a recursive spinlock
> and hence a freeze.
>
> Fixes: b9439491055a ("iwlwifi: pcie: keep the NIC awake when commands are in flight")
> Reported-by: Janusz Dziedzic <janusz.dziedzic@gmail.com>
> Reviewed-by: Johannes Berg <johannes.berg@intel.com>
> Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

Ah, this is why my laptop was hanging during boot with latest
wireless-testing? Thanks for fixing this. 

FWIW:

Tested-by: Kalle Valo <kvalo@adurom.com>

-- 
Kalle Valo