CVS commit: [netbsd-10] src/sys

["Martin Husemann" <martin%netbsd.org@localhost>]

Module Name:    src
Committed By:   martin
Date:           Thu Apr 18 18:22:10 UTC 2024

Modified Files:
        src/sys/kern [netbsd-10]: init_main.c kern_hook.c vfs_mount.c
        src/sys/miscfs/procfs [netbsd-10]: procfs.h procfs_subr.c
            procfs_vfsops.c procfs_vnops.c

Log Message:
Pull up following revision(s) (requested by hannken in ticket #668):

        sys/miscfs/procfs/procfs.h: revision 1.83
        sys/miscfs/procfs/procfs.h: revision 1.84
        sys/kern/vfs_mount.c: revision 1.104
        sys/miscfs/procfs/procfs_vnops.c: revision 1.230
        sys/kern/init_main.c: revision 1.547
        sys/kern/kern_hook.c: revision 1.15
        sys/miscfs/procfs/procfs_vfsops.c: revision 1.112
        sys/miscfs/procfs/procfs_vfsops.c: revision 1.113
        sys/miscfs/procfs/procfs_vfsops.c: revision 1.114
        sys/miscfs/procfs/procfs_subr.c: revision 1.117

Print dangling vnode before panic() to help debug.

PR kern/57775 ""panic: unmount: dangling vnode" while umounting procfs"
Protect kernel hooks exechook, exithook and forkhook with rwlock.

Lock as writer on establish/disestablish and as reader on list traverse.

For exechook ride "exec_lock" as it is already take as reader when
traversing the list.  Add local locks for exithook and forkhook.

Move exec_init before signal_init as signal_init calls exechook_establish()
that needs "exec_lock".

PR kern/39913 "exec, fork, exit hooks need locking"

Add a hashmap to access all procfs nodes by pid.

Using the exechook to revoke procfs nodes is racy and may deadlock:
one thread runs doexechooks() -> procfs_revoke_vnodes() and wants to suspend
the file system for vgone(), while another thread runs a forced unmount,
has the file system suspended, tries to disestablish the exechook and
waits for doexechooks() to complete.

Establish/disestablish the exechook on module load/unload instead
mount/unmount and use the hashmap to access all procfs nodes for this pid.

May fix PR kern/57775 ""panic: unmount: dangling vnode" while umounting procfs"

Remove all procfs nodes for this process on process exit.


To generate a diff of this commit:
cvs rdiff -u -r1.541 -r1.541.2.1 src/sys/kern/init_main.c
cvs rdiff -u -r1.14 -r1.14.2.1 src/sys/kern/kern_hook.c
cvs rdiff -u -r1.101 -r1.101.2.1 src/sys/kern/vfs_mount.c
cvs rdiff -u -r1.82 -r1.82.4.1 src/sys/miscfs/procfs/procfs.h
cvs rdiff -u -r1.116 -r1.116.20.1 src/sys/miscfs/procfs/procfs_subr.c
cvs rdiff -u -r1.111 -r1.111.4.1 src/sys/miscfs/procfs/procfs_vfsops.c
cvs rdiff -u -r1.229 -r1.229.4.1 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.