Re: [PATCH 4.1] rtlwifi: Remove the clear interrupt routine from all drivers

[Kalle Valo <kvalo@codeaurora.org>]

Larry Finger <Larry.Finger@lwfinger.net> writes:

> From: Vincent Fann <vincent_fann@realtek.com>
>
> Several of these drivers have there TX randomly blocked for 3~5 seconds while
> measuring tx throughput (iperf). The root couse happens in rtl_pci_flush().
> The function uses a while-loop to wait for TX queue length to decrease to 0.
> The TX queue length counts the number of packets that are queued in the driver.
> The driver relys on the TX OK interrupt to return skb and reduce TX queue length.
>
> The interrupt subroutine disables interupts, reads the interrupt registers, and
> then clears the registers in the beginning of _rtl_pci_interrupt(). After all
> interupts process are finished, the driver invokes enable_interrupt() to enable
> interupts. This behavior is normal for an interrupt subroutine.
>
> But enable_interrupt() invokes clear_interrupt() again. This unexpected interrupt
> clearing may cleari me fresh TX OK interrupts. These missing interrupts cause TX
> queue length to never reduce to 0i, which causes rtl_pci_flush() to be stuck in
> unterminated while-loop.
>
> This patch removes clear_interrupt() in enable_interrupt() to avoid this behavior.
>
> Signed-off-by: Vincent Fann <vincent_fann@realtek.com>
> Signed-off-by: Shao Fu <shaofu@realtek.com>
> Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
> Cc: Stable <stable@vger.kernel.org> [3.18+]
> ---
>
> Kalle,
>
> This patch is a little large for the current kernel and stable; however, it only
> deletes code that is clearly wrong. I hope it will be OK.

This isn't a recent regression nor a crasher (or similar) so I can't
really justify to send this to 4.1 this late. The way I see it this
could easily wait for 4.2, right?

-- 
Kalle Valo