On Sat, Dec 03, 2022 at 03:40:13PM +0100, Martin Husemann wrote: > On Thu, Jul 07, 2022 at 09:22:42PM +0200, Martin Husemann wrote: > > I guess in older times ci->ci_want_resched was used as a boolean flag, so > > only > > 0 or !0 did matter - but nowadays it is a flag word of various bits: > > > > #define RESCHED_REMOTE 0x01 /* request is for a remote CPU > > */ > > #define RESCHED_IDLE 0x02 /* idle LWP observed */ > > #define RESCHED_UPREEMPT 0x04 /* immediate user ctx switch */ > > #define RESCHED_KPREEMPT 0x08 /* immediate kernel ctx switch > > */ > > > > > > The MD usage of ci_data.cpu_softints on powerpc is a bitmask of pending > > softint IPLs, which could easily collide with above flags. > > Even if this (currently) does not seem to cause issues, mixing bits from > different bitsets is wrong, so I'd like to commit the originaly proposed > fix (only ever clear all bits).
I agree this seems best. > Additionaly I'd like to commit something like the second change below, fixing > an issue when creating new lwps (that neither should have ASTs pending nor > own the altivec psu). I am not sure if the PSL_VEC is the only bit that > should be cleared here. the only bits in md_flags that can be set are PSL_VEC and PSL_SE, but nothing ever looks at the PSL_SE bit in this field. so you skip copying the whole l_md structure and just set both md_flags and md_astpending to zero. the code in process_machdep.c that sets and clears PSL_SE in md_flags could also be removed. -Chuck > Martin > > > Index: kern/kern_synch.c > =================================================================== > RCS file: /cvsroot/src/sys/kern/kern_synch.c,v > retrieving revision 1.352 > diff -u -p -r1.352 kern_synch.c > --- kern/kern_synch.c 26 Oct 2022 23:23:28 -0000 1.352 > +++ kern/kern_synch.c 3 Dec 2022 14:14:38 -0000 > @@ -554,7 +554,8 @@ nextlwp(struct cpu_info *ci, struct sche > * the update to ci_want_resched will become globally visible before > * the release of spc_mutex becomes globally visible. > */ > - ci->ci_want_resched = ci->ci_data.cpu_softints; > + if (ci->ci_data.cpu_softints == 0) > + ci->ci_want_resched = 0; > > return newl; > } > Index: arch/powerpc/powerpc/vm_machdep.c > =================================================================== > RCS file: /cvsroot/src/sys/arch/powerpc/powerpc/vm_machdep.c,v > retrieving revision 1.104 > diff -u -p -r1.104 vm_machdep.c > --- arch/powerpc/powerpc/vm_machdep.c 6 Jul 2020 10:52:12 -0000 1.104 > +++ arch/powerpc/powerpc/vm_machdep.c 3 Dec 2022 14:14:38 -0000 > @@ -95,8 +95,13 @@ cpu_lwp_fork(struct lwp *l1, struct lwp > struct pcb * const pcb1 = lwp_getpcb(l1); > struct pcb * const pcb2 = lwp_getpcb(l2); > > - /* Copy MD part of lwp and set up user trapframe pointer. */ > + /* > + * Copy MD part of lwp, fix up for new lwp and set up user > + * trapframe pointer. > + */ > l2->l_md = l1->l_md; > + l2->l_md.md_flags &= ~PSL_VEC; > + l2->l_md.md_astpending = 0; > l2->l_md.md_utf = trapframe(l2); > > /* Copy PCB. */
