LDP
/
man-pages
mirror of https://github.com/mkerrisk/man-pages
0
1
Fork 0
Code Releases Activity

tkill.2: srcfix: FIXME tidy-up 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2016-10-29 12:31:16 +02:00
parent cda56b8eed
commit eec5c0d0cc
1 changed files with 20 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
man2/tkill.2
View File

@ -61,27 +61,29 @@ terminates and its thread ID is recycled.
Avoid using this system call. Avoid using this system call.
.\" FIXME Maybe say something about the following: .\" FIXME Maybe say something about the following:
.\" http://sourceware.org/bugzilla/show_bug.cgi?id=12889 .\" http://sourceware.org/bugzilla/show_bug.cgi?id=12889
.\" Rich Felker <bugdal@aerifal.cx>
.\" There is a race condition in pthread_kill: it is possible that,
.\" between the time pthread_kill reads the pid/tid from the target
.\" thread descriptor and the time it makes the tgkill syscall,
.\" the target thread terminates and the same tid gets assigned
.\" to a new thread in the same process.
.\" .\"
.\" (The tgkill syscall was designed to eliminate a similar race .\" Quoting Rich Felker <bugdal@aerifal.cx>:
.\" condition in tkill, but it only succeeded in eliminating races
.\" where the tid gets reused in a different process, and does not
.\" help if the same tid gets assigned to a new thread in the
.\" same process.)
.\" .\"
.\" The only solution I can see is to introduce a mutex that ensures .\" There is a race condition in pthread_kill: it is possible that,
.\" that a thread cannot exit while pthread_kill is being called on it. .\" between the time pthread_kill reads the pid/tid from the target
.\" thread descriptor and the time it makes the tgkill syscall,
.\" the target thread terminates and the same tid gets assigned
.\" to a new thread in the same process.
.\" .\"
.\" Note that in most real-world situations, like almost all race .\" (The tgkill syscall was designed to eliminate a similar race
.\" conditions, this one will be extremely rare. To make it .\" condition in tkill, but it only succeeded in eliminating races
.\" measurable, one could exhaust all but 1-2 available pid values, .\" where the tid gets reused in a different process, and does not
.\" possibly by lowering the max pid parameter in /proc, forcing .\" help if the same tid gets assigned to a new thread in the
.\" the same tid to be reused rapidly. .\" same process.)
.\"
.\" The only solution I can see is to introduce a mutex that ensures
.\" that a thread cannot exit while pthread_kill is being called on it.
.\"
.\" Note that in most real-world situations, like almost all race
.\" conditions, this one will be extremely rare. To make it
.\" measurable, one could exhaust all but 1-2 available pid values,
.\" possibly by lowering the max pid parameter in /proc, forcing
.\" the same tid to be reused rapidly.
These are the raw system call interfaces, meant for internal These are the raw system call interfaces, meant for internal
thread library use. thread library use.