we can't do an SA context switch after all, we need to clear the sau from
the LWP's arg. sa_switch() frees the sau in this case, but if we don't
reset the LWP's state and the process exits, then the exiting LWP will
try to free the sau again.
also, change the sadebug printf stuff to use printf_nolog(), since
otherwise we deadlock because we're already holding sched_lock and
the normal printf() will try to wakeup the log reader.
since both pool_get() and pool_put() can call wakeup().
instead, allocate the struct sadata_upcall before taking
sched_lock in mi_switch() and free it after releasing sched_lock.
clean up some modularity warts by adding a callback to
struct sadata_upcall for freeing sa_arg.
doing a context switch. use this on sparc and sparc64 to avoid trying
to access user memory (writing the register windows back to the stack)
in this case (since it's both unnecessary and wrong).
do not leak siginfo structures.
Note that in the cases of trap signals and timer events, losing this
information could be very bad; right now it will cause us to spin until the
process is SIGKILLed.
"Needs work."
- move per VP data into struct sadata_vp referenced from l->l_savp
* VP id
* lock on VP data
* LWP on VP
* recently blocked LWP on VP
* queue of LWPs woken which ran on this VP before sleep
* faultaddr
* LWP cache for upcalls
* upcall queue
- add current concurrency and requested concurrency variables
- make process exit run LWP on all VPs
- make signal delivery consider all VPs
- make timer events consider all VPs
- add sa_newsavp to allocate new sadata_vp structure
- add sa_increaseconcurrency to prepare new VP
- make sys_sa_setconcurrency request new VP or wakeup idle VP
- make sa_yield lower current concurrency
- set sa_cpu = VP id in upcalls
- maintain cached LWPs per VP
an offset between ss_sp and struct sa_stackinfo_t (located in struct
__pthread_st) when calling sa_register. The kernel increments the
sast_gen counter in struct sastack when an upcall stack is used.
libpthread increments the sasi_stackgen counter in struct
sa_stackinfo_t when an upcall stack is freed. The kernel compares the
two counters to decide if a stack is free or in use.
- add struct sa_stackinfo_t with sasi_stackgen to count stack use in
userland
- add sast_gen to struct sastack to count stack use in kernel
- add SA_FLAG_STACKINFO to enable the stackinfo_offset argument in the
sa_register syscall
- add sa_stackinfo_offset to struct sadata for offset between ss_sp
and struct sa_stackinfo_t
- add ssize_t stackinfo_offset argument to sa_register, initialize
struct sadata's sa_stackinfo_offset from it if SA_FLAG_STACKINFO is
set
- add sa_getstack, sa_getstack0, sa_stackused and sa_setstackfree
functions to find/use/free upcall stacks and use these where
appropriate
- don't record stack for upcall in sa_upcall0
- pass sau to sa_switchcall instead of l2 (l2 = curlwp in sa_switchcall)
- add sa_vp_blocker to struct sadata to pass recently blocked lwp to
sa_switchcall
- delay finding a stack for blocked upcalls to sa_switchcall
- add sa_stacknext to struct sadata pointing to next most likely free
upcall stack; also g/c sa_stackslist in struct sadata and sast_list
in struct sastack
- add L_SA_WOKEN flag: LWP is on sa_woken queue
- add L_SA_RECYCLE flag: LWP should be recycled in sa_setwoken
- replace l_upcallstack with L_SA_WOKEN/L_SA_RECYCLE/L_SA_BLOCKING
flags
- g/c now unused sast_blocker in struct sastack
- make sa_switchcall, sa_upcall0 and sa_upcall_getstate static in
kern_sa.c
- call sa_upcall_userret only once in userret
- split sa_makeupcalls out of sa_upcall_userret and use to process
the sa_upcalls queue
- on process exit: mark LWPs sleeping in saunblock interruptible; also
there are no LWPs sleeping on l->l_upcallstack anymore; also clear
sa_wokenq_head to prevent unblocked upcalls
additional changes:
- cleanup timerupcall sa_vp == curlwp check
- add check in sa_yield if we didn't block on our way here and we
wouldn't any longer be the LWP on the VP
- invalidate sa_vp_ofaultaddr after resolving pagefault
- always wait for unblocked upcall if we have to continue a blocked
thread.
=> removes wakeup from sys_sa_stacks when a stack is returned.
=> avoids extra sa_unblockyield syscall when unblocked upcall is
delivered before blocked upcall is processed.
=> avoids double pagefault if we continued a thread before the
pagefault was resolved.
=> avoids losing unblocked state if we continued a thread after
skipping the unblocked upcall.
- use splay tree for the pagefault check if the thread was running on
an upcall stack.
=> removes the limitation that all upcall stacks need to be
adjoining and that all upcall stacks have to be loaded with the
1st sys_sa_stacks call.
=> enables keeping information associated with a stack in the kernel
which makes it simpler to find out which LWP is using a stack.
=> allows increasing the SA_MAXNUMSTACKS without having to
allocate an array of that size.
This should fix PR 23418 which was also reported by Thomas Klausner and
Ian Fry (who also provided core dumps for analysis - thanks!).
Also g/c sa_yieldcall since it's now safe to put LWPs back into the cache.
Also return stacks in failure case.
combined. Also prepare for adding VP repossession later.
- kern_sa.c: sa_yield/sa_switch: detect if there are pending unblocked
upcalls.
- kern_sa.c: sa_unblock_userret/sa_setwoken: queue LWPs about to invoke
an unblocked upcall on the sa_wokenq. put queued LWPs in a state where
they can be put in the cache. notify LWP on the VP about pending
upcalls.
- kern_sa.c: sa_upcall_userret: check sa_wokenq for pending upcalls,
generate unblocked upcalls with multiple event sas
- kern_sa.c: sa_vp_repossess/sa_vp_donate: g/c, restore original
sa_vp_repossess
General idea: only consider the LWP on the VP for signal delivery, all
other LWPs are either asleep or running from waking up until repossessing
the VP.
- in kern_sig.c:kpsignal2: handle all states the LWP on the VP can be in
- in kern_sig.c:proc_stop: only try to stop the LWP on the VP. All other
LWPs will suspend in sa_vp_repossess() until the VP-LWP donates the VP.
Restore original behaviour (before SA-specific hacks were added) for
non-SA processes.
- in kern_sig.c:proc_unstop: only return the LWP on the VP
- handle sa_yield as case 0 in sa_switch instead of clearing L_SA, add an
L_SA_YIELD flag
- replace sa_idle by L_SA_IDLE flag since it was either NULL or == sa_vp
Also don't output itimerfire overrun warning if the process is already
exiting.
Also g/c sa_woken because it's not used.
Also g/c some #if 0 code.
generate unblocked upcalls in sa_unblock_userret(), before signal
delivery/p_userret handling in userret().
Also defer getting state for preempted upcalls because on some ports
preemption can happen between sa_unblock_userret() and sa_upcall_userret().
its state is saved:
- don't sa_putcachelwp() in sa_vp_repossess/sa_vp_donate
- only defer saving the event LWP's state
- sa_putcachelwp() after the interrupted LWP's state is saved
- prevent BLOCKED upcalls on double page faults and during upcalls
- make libpthread handle blocked threads which hold locks
- prevent UNBLOCKED upcalls from overtaking their BLOCKED upcall
this adds a new syscall sa_unblockyield
see also http://mail-index.netbsd.org/tech-kern/2003/09/15/0020.html
The patch below (hopefully) improves some signaling problems
found by Nathan.
It also contains some cleanup of the sa_upcall_userret() function
removing any sleep calls using PCATCH.
Unblocked threads now only use an upcall stack after they
acquire the virtual CPU.
This prevents unblocked threads from stealing all available
upcall stacks.
Tested by Nick Hudson.
