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| author | Konstantin Belousov <kib@FreeBSD.org> | 2022-12-05 22:43:18 +0000 |
|---|---|---|
| committer | Konstantin Belousov <kib@FreeBSD.org> | 2022-12-22 21:11:35 +0000 |
| commit | 0e07241c372d7352537a4a786c96a580a721be3c (patch) | |
| tree | c339b5e684fbb0db895337d796f2571437bfac6c | |
| parent | f0592b3c8dd8e172f0e7165c11371108d4d8838d (diff) | |
| download | src-0e07241c372d7352537a4a786c96a580a721be3c.tar.gz src-0e07241c372d7352537a4a786c96a580a721be3c.zip | |
ptrace(2): explain how to select specific thread to operate on
Requested by: emaste
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D37590
| -rw-r--r-- | lib/libc/sys/ptrace.2 | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/lib/libc/sys/ptrace.2 b/lib/libc/sys/ptrace.2 index 4589fac92d26..01d83897a78b 100644 --- a/lib/libc/sys/ptrace.2 +++ b/lib/libc/sys/ptrace.2 @@ -122,6 +122,25 @@ Kernel drops any signals queued to the traced children, which could be either generated by not yet consumed debug events, or sent by other means, the later should not be done anyway. +.Sh SELECTING THE TARGET +The +.Fa pid +argument of the call specifies the target on which to perform +the requested operation. +For operations affecting the global process state, the process ID +is typically passed there. +Similarly, for operations affecting only a thread, the thread ID +needs to be passed. +.Pp +Still, for global operations, the ID of any thread can be used as the +target, and system will perform the request on the process owning +that thread. +If a thread operation got the process ID as +.Fa pid , +the system randomly selects a thread from among the threads owned +by the process. +For single-threaded processes there is no difference between specifying +process or thread ID as the target. .Sh DISABLING PTRACE The .Nm |