libthr.3: describe SIGTHR

Explain how SIGTHR is used and that it should be not touched by user
code.  Note about SIGLIBRT.

Reviewed by:	emaste
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Differential revision:	https://reviews.freebsd.org/D56384

This commit is contained in:

Konstantin Belousov

2026-04-14 02:42:51 +03:00

parent fa912e3b9b

commit 934a35ac2b

1 changed files with 19 additions and 0 deletions

lib/libthr/libthr.3

+19

View File

@@ -269,6 +269,25 @@ the critical section.
 This should be taken into account when interpreting
 .Xr ktrace 1
 logs.
 .Pp
 The
 .Nm
 library uses the
 .Va SIGTHR
 signal for internal operations, in particular,
 for cancellation requests.
 This signal's masking and disposition is controlled by the library,
 and user programs should not try to modify them.
 The library interposes functions controlling signals to prevent
 inadvertent modifications and to guard portable code against
 exposure to
 .Va SIGTHR .
 .Pp
 Note: similarly, the
 .Va SIGLIBRT
 signal is reserved for use by
 .Lb librt ,
 and should be not modified by users.
 .Sh PROCESS-SHARED SYNCHRONIZATION OBJECTS
 In the
 .Li libthr