Re: [PATCH 03/14] scsi: qla4xxx: qla4_82xx_crb_win_lock(): Remove in_interrupt().

Daniel Wagner
2020-11-30T13:55:04Z

On Thu, Nov 26, 2020 at 02:29:41PM +0100, Sebastian Andrzej Siewior wrote:
> From: "Ahmed S. Darwish" <a.darwish@linutronix.de>
>
> qla4_82xx_crb_win_lock() spins on a certain hardware state until it's
> updated. At the end of each spin, if in_interrupt() is true, it does 20
> loops of cpu_relax(). Otherwise, it yields the CPU.
>
> The in_interrupt() macro is ill-defined as it does not provide what the
> name suggests, and it does not catch the intended use-case here.
>
> qla4_82xx_crb_win_lock() is always invoked with scsi_qla_host::hw_lock
> acquired, with disabled interrupts. If the caller is in process context,
> as in qla4_82xx_need_reset_handler(), then in_interrupt() will return
> false even though it is not allowed to call schedule().
>
> Remove the in_interrupt() check.
>
> Change qla4_82xx_crb_win_lock() specification to a purely atomic
> function. Mark it as static, remove its forward declaration, and move it
> above its callers. To avoid hammering the PCI bus while spinning, use a
> 10 micro-second delay instead of cpu_relax().
>
> Fixes: f4f5df23bf72 ("[SCSI] qla4xxx: Added support for ISP82XX")
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Cc: Nilesh Javali <njavali@marvell.com>
> Cc: Manish Rangankar <mrangankar@marvell.com>
> Cc: <GR-QLogic-Storage-Upstream@marvell.com>

Reviewed-by: Daniel Wagner <dwagner@suse.de>