On Wed, Feb 10, 2021 at 11:50:45AM +0000, Song Bao Hua (Barry Song) wrote:
-----Original Message----- From: Andy Shevchenko [mailto:andy.shevchenko@gmail.com] Sent: Wednesday, February 10, 2021 11:51 PM On Wed, Feb 10, 2021 at 5:43 AM luojiaxing luojiaxing@huawei.com wrote:
On 2021/2/9 17:42, Andy Shevchenko wrote:
...
Between IRQ handler A and IRQ handle A, it's no need for a SLIS.
Right, but it's not the case in the patches you provided.
The code still holds spin_lock. So if two cpus call same IRQ handler, spin_lock makes them spin; and if interrupts are threaded, spin_lock makes two threads run the same handler one by one.
If you run on an SMP system and it happens that spin_lock_irqsave() just immediately after spin_unlock(), you will get into the troubles. Am I mistaken?
I think this entire activity is a carefully crafted mine field for the future syzcaller and fuzzers alike. I don't believe there are no side effects in a long term on all possible systems and configurations (including forced threaded IRQ handlers).
I would love to see a better explanation in the commit message of such patches which makes it clear that there are *no* side effects.
For time being, NAK to the all patches of this kind.