Dear Experts
I am little confused now with GIC handling of interrupt in case of Linux.
As I understood. GIC level interrupt can be at following stage
1) Inactive : No interrupt pending
2) Pending : Interrupt raised by IP , acknowlged by GIC, and forwarded to CPU
3) Active: Interrupt acknowlged by core and under servicing
4) Active and Pending: CPU is serving interrupt and IP raised by same Interrupt
Coming to Linux code
Assuming IP interrupt is low level trigger
1) IP raise interrupt, GIC deliver it to CPU
2) Linux acknowlegd to GIC, and move inteerupt to active state .
3) Before calling IP specific handler (Where IP interrupt's line status will be changed to high) , Linux mark this interrupt as EOI (As I understood this is moving IT to Inactive)
https://elixir.bootlin.com/linux/v6.8-rc4/source/drivers/irqchip/irq-gic.c#L351
Now after this line, at GIC level interrupt moved to Inactive state, IP line is still low
4) IP specific handler is getting called.
Confusion, I have how GIC avoids condition between 3 and 4.
Shouldn't this be better to call IP handler first then clear IT at GIC level.
I may be wrong , please suggest