PR/57775 CVS commit: [netbsd-10] src/sys

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

The following reply was made to PR kern/57775; it has been noted by GNATS.

From: "Martin Husemann" <martin%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/57775 CVS commit: [netbsd-10] src/sys
Date: Thu, 18 Apr 2024 18:22:10 +0000

 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.