Module Name: src
Committed By: martin
Date: Wed Nov 20 14:01:59 UTC 2024
Modified Files:
src/sys/compat/netbsd32 [netbsd-9]: netbsd32_ioctl.c
src/sys/ddb [netbsd-9]: db_xxx.c
src/sys/kern [netbsd-9]: kern_descrip.c kern_event.c kern_sig.c
subr_exec_fd.c sys_aio.c sys_descrip.c sys_select.c uipc_socket2.c
uipc_usrreq.c
src/sys/miscfs/fdesc [netbsd-9]: fdesc_vnops.c
src/sys/miscfs/procfs [netbsd-9]: procfs_vnops.c
Log Message:
Pull up following revision(s) (requested by riastradh in ticket #1921):
sys/kern/kern_event.c: revision 1.106
sys/kern/sys_select.c: revision 1.51
sys/kern/subr_exec_fd.c: revision 1.10
sys/kern/sys_aio.c: revision 1.46
sys/kern/kern_descrip.c: revision 1.244
sys/kern/kern_descrip.c: revision 1.245
sys/ddb/db_xxx.c: revision 1.72
sys/ddb/db_xxx.c: revision 1.73
sys/miscfs/fdesc/fdesc_vnops.c: revision 1.132
sys/kern/uipc_usrreq.c: revision 1.195
sys/kern/sys_descrip.c: revision 1.36
sys/kern/uipc_usrreq.c: revision 1.196
sys/kern/uipc_socket2.c: revision 1.135
sys/kern/uipc_socket2.c: revision 1.136
sys/kern/kern_sig.c: revision 1.383
sys/kern/kern_sig.c: revision 1.384
sys/compat/netbsd32/netbsd32_ioctl.c: revision 1.107
sys/miscfs/procfs/procfs_vnops.c: revision 1.208
sys/kern/subr_exec_fd.c: revision 1.9
sys/kern/kern_descrip.c: revision 1.252
(all via patch)
Load struct filedesc::fd_dt with atomic_load_consume.
Exceptions: when fd_refcnt <= 1, or when holding fd_lock.
While here:
- Restore KASSERT(mutex_owned(&fdp->fd_lock)) in fd_unused.
=> This is used only in fd_close and fd_abort, where it holds.
- Move bounds check assertion in fd_putfile to where it matters.
- Store fd_dt with atomic_store_release.
- Move load of fd_dt under lock in knote_fdclose.
- Omit membar_consumer in fdesc_readdir.
=> atomic_load_consume serves the same purpose now.
=> Was needed only on alpha anyway.
Load struct fdfile::ff_file with atomic_load_consume.
Exceptions: when we're only testing whether it's there, not about to
dereference it.
Note: We do not use atomic_store_release to set it because the
preceding mutex_exit should be enough.
(That said, it's not clear the mutex_enter/exit is needed unless
refcnt > 0 already, in which case maybe it would be a win to switch
from the membar implied by mutex_enter to the membar implied by
atomic_store_release -- which I would generally expect to be much
cheaper. And a little clearer without a long comment.)
kern_descrip.c: Fix membars around reference count decrement.
In general, the `last one out hit the lights' style of reference
counting (as opposed to the `whoever's destroying must wait for
pending users to finish' style) requires memory barriers like so:
... usage of resources associated with object ...
membar_release();
if (atomic_dec_uint_nv(&obj->refcnt) != 0)
return;
membar_acquire();
... freeing of resources associated with object ...
This way, all usage happens-before all freeing. This fixes several
errors:
- fd_close failed to ensure whatever its caller did would
happen-before the freeing, in the case where another thread is
concurrently trying to close the fd (ff->ff_file == NULL).
Fix: Add membar_release before atomic_dec_uint(&ff->ff_refcnt) in
that branch.
- fd_close failed to ensure all loads its caller had issued will have
happened-before the freeing, in the case where the fd is still in
use by another thread (fdp->fd_refcnt > 1 and ff->ff_refcnt-- > 0).
Fix: Change membar_producer to membar_release before
atomic_dec_uint(&ff->ff_refcnt).
- fd_close failed to ensure that any usage of fp by other callers
would happen-before any freeing it does.
Fix: Add membar_acquire after atomic_dec_uint_nv(&ff->ff_refcnt).
- fd_free failed to ensure that any usage of fdp by other callers
would happen-before any freeing it does.
Fix: Add membar_acquire after atomic_dec_uint_nv(&fdp->fd_refcnt).
While here, change membar_exit -> membar_release. No semantic
change, just updating away from the legacy API.
To generate a diff of this commit:
cvs rdiff -u -r1.103.2.2 -r1.103.2.3 src/sys/compat/netbsd32/netbsd32_ioctl.c
cvs rdiff -u -r1.71 -r1.71.22.1 src/sys/ddb/db_xxx.c
cvs rdiff -u -r1.243.4.2 -r1.243.4.3 src/sys/kern/kern_descrip.c
cvs rdiff -u -r1.104.4.2 -r1.104.4.3 src/sys/kern/kern_event.c
cvs rdiff -u -r1.364.2.9 -r1.364.2.10 src/sys/kern/kern_sig.c
cvs rdiff -u -r1.8 -r1.8.4.1 src/sys/kern/subr_exec_fd.c
cvs rdiff -u -r1.44 -r1.44.4.1 src/sys/kern/sys_aio.c
cvs rdiff -u -r1.33 -r1.33.2.1 src/sys/kern/sys_descrip.c
cvs rdiff -u -r1.46 -r1.46.2.1 src/sys/kern/sys_select.c
cvs rdiff -u -r1.134.2.2 -r1.134.2.3 src/sys/kern/uipc_socket2.c
cvs rdiff -u -r1.194.2.1 -r1.194.2.2 src/sys/kern/uipc_usrreq.c
cvs rdiff -u -r1.130.4.1 -r1.130.4.2 src/sys/miscfs/fdesc/fdesc_vnops.c
cvs rdiff -u -r1.206.4.2 -r1.206.4.3 src/sys/miscfs/procfs/procfs_vnops.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
