linuxkpi: Fix mod_timer and del_timer_sync

[manu]

Summary

mod_timer is supposed to return 1 if the modified timer was pending, which
is exactly what callout_reset does so return this value directly.
The only not handled case is when callout_reset fails, for now returns 0 as if the timer
wasn't modified.
del_timer_sync returns int so add a function and handle that.

[• hselasky]

sys/compat/linuxkpi/common/include/linux/timer.h

86 ↗

(On Diff #72189)

This is wrong. callout_drain() is not the same like callout_stop() as used by del_timer(). Please read the callout implementation carefully.

sys/compat/linuxkpi/common/src/linux_compat.c

1911 ↗

(On Diff #72189)

Please read the callout_reset() code that you return exactly what you want!

[manu]

sys/compat/linuxkpi/common/include/linux/timer.h

86 ↗

(On Diff #72189)

oops sorry, I'll change that.

sys/compat/linuxkpi/common/src/linux_compat.c

1911 ↗

(On Diff #72189)

?

[• hselasky]

sys/compat/linuxkpi/common/src/linux_compat.c

1911 ↗

(On Diff #72189)

From what I know callout functions can return 1,0,-1. Are you sure callout reset only returns 1/0 ?

[manu]

sys/compat/linuxkpi/common/src/linux_compat.c

1911 ↗

(On Diff #72189)

Oh mhm, right, I guess I should just ignore <0 like we do now.
I'll change that.

[• hselasky]

sys/compat/linuxkpi/common/src/linux_compat.c

1908 ↗

(On Diff #72220)

Callout reset never fails. Please remove or update this comment.

Either it:
starts timer from clear (0)
or re-starts timer (1)

MPASS(ret == 0 || ret == 1);

return (ret == 1);

[manu]

sys/compat/linuxkpi/common/src/linux_compat.c

1908 ↗

(On Diff #72220)

So my original code was right ?

[• hselasky]

sys/compat/linuxkpi/common/src/linux_compat.c

1908 ↗

(On Diff #72220)

Yes, looks like, except for only testing ret == 1.

Add an assert for the sake of future changes in callout APIs.

[• hselasky]

Beware that older versions of FreeBSD behave different w.r.t the return values from FreeBSD callout APIs. Be careful when MFC-ing to 11 and older.