git: kernel and libc - Reimplement lwp_setname*() using /dev/lpmap

Matthew Dillon dillon at
Tue Nov 12 11:09:53 PST 2019

commit e7126f0a1027db73e43270705209e5b4120d77e5
Author: Matthew Dillon <dillon at>
Date:   Tue Nov 12 11:00:42 2019 -0800

    kernel and libc - Reimplement lwp_setname*() using /dev/lpmap
    * Generally speaking we are implementing the features necessary
      to allow per-thread titling set via pthread_set_name_np() to
      show up in 'ps' output, and to use lpmap to make it fast.
    * The lwp_setname() system call now stores the title in
    * Implement a libc fast-path for lwp_setname() using lpmap.
      If called more than 10 times, libc will use lpmap for any
      further calls, which omits the need to make any system calls.
    * setproctitle() now stores the title in upmap->proc_title[]
      instead of replacing proc->p_args.  proc->p_args is now no
      longer modified from its original contents.
    * The kernel now includes lpmap->thread_title[] in the following
      priority order when retrieving the process command line:
      lpmap->thread_title[]		User-supplied thread title, if not empty
      upmap->proc_title[]		User-supplied process title, if not empty
      proc->p_args			Original process arguments (no longer modified)
    * Put the TID in /dev/lpmap for convenient access
    * Enhance the KERN_PROC_ARGS sysctl to allow the TID to be specified.
      The sysctl now accepts { KERN_PROC, KERN_PROC_ARGS, pid, tid }
      in addition to the existing { KERN_PROC, KERN_PROC_ARGS, pid }
      Enhance libkvm to use the new feature.  libkvm will fall-back to
      the old version if necessary.

Summary of changes:
 lib/libc/upmap/                        |   2 +-
 .../upmap/{ukp_setproctitle.c => ukp_setname.c}    |  49 +++++---
 lib/libkvm/kvm_proc.c                              |  23 +++-
 sys/kern/kern_proc.c                               | 128 ++++++++++++++++++---
 sys/kern/kern_prot.c                               |  29 +++--
 sys/sys/proc.h                                     |   1 +
 sys/sys/upmap.h                                    |   3 +-
 sys/vfs/procfs/procfs_status.c                     |  20 +++-
 8 files changed, 200 insertions(+), 55 deletions(-)
 copy lib/libc/upmap/{ukp_setproctitle.c => ukp_setname.c} (61%)

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