Re: [PATCH v2 7/9] gpio: 104-idi-48: make use of raw_spinlock variants

Linus Walleij
2017-03-28T09:12:01Z

On Wed, Mar 22, 2017 at 1:44 PM, William Breathitt Gray
<vilhelm.gray@gmail.com> wrote:
> On Tue, Mar 21, 2017 at 05:43:07PM -0500, Julia Cartwright wrote:
>>The 104-idi-48 gpio driver currently implements an irq_chip for handling
>>interrupts; due to how irq_chip handling is done, it's necessary for the
>>irq_chip methods to be invoked from hardirq context, even on a a
>>real-time kernel. Because the spinlock_t type becomes a "sleeping"
>>spinlock w/ RT kernels, it is not suitable to be used with irq_chips.
>>
>>A quick audit of the operations under the lock reveal that they do only
>>minimal, bounded work, and are therefore safe to do under a raw spinlock.
>>
>>Signed-off-by: Julia Cartwright <julia@ni.com>
>
> Hi Julia,
>
> This driver also uses a second spinlock_t, called ack_lock, to prevent
> reentrance into the idi_48_irq_handler function. Should ack_lock also be
> implemented as a raw_spinlock_t?

Hm, can I apply this one patch or not?

Linus Walleij