- 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.
whether there is anything to do - almost as if it were a predicate
test outside of a condition wait. This prevents returning to userland
when tsleep() has woken up spuriously, such as from a signal that was
caught and then removed by a tracing process.
Kills off some double-stops in GDB due to signals as well as a couple
of pthread__idle assertions when detaching from a process.
XXX stopping inside tsleep, via CURSIG(), is evil.
(XXX sa_yieldcall() and sa_switchcall() should be combined and take
arg as the function to call, but I'm somewhat nervous about void *
vs. void (*)()).
use 'l' for sa_yield() tsleep call; sa->sa_idle == l there
add DIAGNOSTIC printf on one more place in sa_upcall_userret() where
we kill process with SIGILL
being woken up by the the reaper when a child process is cleaned up
(SIGCHLD will still cause this to run, and threads actually waiting
for the child will still see the wakeup, of course).
Should fix various spurious wakeups that manifest as assertion
failures in pthread__idle().
malloc types into a structure, a pointer to which is passed around,
instead of an int constant. Allow the limit to be adjusted when the
malloc type is defined, or with a function call, as suggested by
Jonathan Stone.
cl