d/freebsd-nq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Update some signal man pages for multithreading.

Browse Source
This commit is contained in:
Jilles Tjoelker 2013-09-06 09:08:40 +00:00
parent 4758b87596
commit 75b1cda430
4 changed files with 41 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
lib/libc/sys/sigaction.2
View File

@ -28,7 +28,7 @@
.\" From: @(#)sigaction.2 8.2 (Berkeley) 4/3/94
.\" $FreeBSD$
.\"
.Dd June 8, 2013
.Dd September 6, 2013
.Dt SIGACTION 2
.Os
.Sh NAME
@ -55,7 +55,7 @@ struct sigaction {
.Sh DESCRIPTION
The system defines a set of signals that may be delivered to a process.
Signal delivery resembles the occurrence of a hardware interrupt:
the signal is normally blocked from further occurrence, the current process
the signal is normally blocked from further occurrence, the current thread
context is saved, and a new one is built.
A process may specify a
.Em handler
@ -64,13 +64,14 @@ to which a signal is delivered, or specify that a signal is to be
A process may also specify that a default action is to be taken
by the system when a signal occurs.
A signal may also be
.Em blocked ,
in which case its delivery is postponed until it is
.Em blocked
for a thread,
in which case it will not be delivered to that thread until it is
.Em unblocked .
The action to be taken on delivery is determined at the time
of delivery.
Normally, signal handlers execute on the current stack
of the process.
of the thread.
This may be changed, on a per-handler basis,
so that signals are taken on a special
.Em "signal stack" .
@ -82,20 +83,30 @@ but other signals may yet occur.
A global
.Em "signal mask"
defines the set of signals currently blocked from delivery
to a process.
The signal mask for a process is initialized
to a thread.
The signal mask for a thread is initialized
from that of its parent (normally empty).
It may be changed with a
.Xr sigprocmask 2
call, or when a signal is delivered to the process.
or
.Xr pthread_sigmask 3
call, or when a signal is delivered to the thread.
.Pp
When a signal
condition arises for a process, the signal is added to a set of
signals pending for the process.
If the signal is not currently
condition arises for a process or thread, the signal is added to a set of
signals pending for the process or thread.
Whether the signal is directed at the process in general or at a specific
thread depends on how it is generated.
For signals directed at a specific thread,
if the signal is not currently
.Em blocked
by the process then it is delivered to the process.
Signals may be delivered any time a process enters the operating system
by the thread then it is delivered to the thread.
For signals directed at the process,
if the signal is not currently
.Em blocked
by all threads then it is delivered to one thread that does not have it blocked
(the selection of which is unspecified).
Signals may be delivered any time a thread enters the operating system
(e.g., during a system call, page fault or trap, or clock interrupt).
If multiple signals are ready to be delivered at the same time,
any signals that could be caused by traps are delivered first.
@ -106,17 +117,17 @@ The set of pending signals is returned by the
.Xr sigpending 2
system call.
When a caught signal
is delivered, the current state of the process is saved,
is delivered, the current state of the thread is saved,
a new signal mask is calculated (as described below),
and the signal handler is invoked.
The call to the handler
is arranged so that if the signal handling routine returns
normally the process will resume execution in the context
normally the thread will resume execution in the context
from before the signal's delivery.
If the process wishes to resume in a different context, then it
If the thread wishes to resume in a different context, then it
must arrange to restore the previous context itself.
.Pp
When a signal is delivered to a process a new signal mask is
When a signal is delivered to a thread a new signal mask is
installed for the duration of the process' signal handler
(or until a
.Xr sigprocmask 2
@ -218,7 +229,7 @@ to
If this bit is set, the system will deliver the signal to the process
on a
.Em "signal stack" ,
specified with
specified by each thread with
.Xr sigaltstack 2 .
.It Dv SA_NODEFER
If this bit is set, further occurrences of the delivered signal are
@ -272,6 +283,11 @@ However, calls that have already committed are not restarted,
but instead return a partial success (for example, a short read count).
.Pp
After a
.Xr pthread_create 3
the signal mask is inherited by the new thread and
the set of pending signals and the signal stack for the new thread are empty.
.Pp
After a
.Xr fork 2
or
.Xr vfork 2

4
lib/libc/sys/sigpending.2
View File

@ -31,7 +31,7 @@
.\" @(#)sigpending.2 8.3 (Berkeley) 1/12/94
.\" $FreeBSD$
.\"
.Dd January 12, 1994
.Dd September 6, 2013
.Dt SIGPENDING 2
.Os
.Sh NAME
@ -47,7 +47,7 @@
The
.Fn sigpending
system call returns a mask of the signals pending for delivery
to the calling process in the location indicated by
to the calling thread or the calling process in the location indicated by
.Fa set .
Signals may be pending because they are currently masked,
or transiently before delivery (although the latter case is not

6
lib/libc/sys/sigreturn.2
View File

@ -28,7 +28,7 @@
.\" @(#)sigreturn.2 8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd June 4, 1993
.Dd September 6, 2013
.Dt SIGRETURN 2
.Os
.Sh NAME
@ -46,7 +46,7 @@ The
system call
allows users to atomically unmask, switch stacks,
and return from a signal context.
The processes signal mask and stack status are
The thread's signal mask and stack status are
restored from the context structure pointed to by
.Fa scp .
The system call does not return;
@ -65,7 +65,7 @@ is set to indicate the error.
The
.Fn sigreturn
system call
will fail and the process context will remain unchanged
will fail and the thread context will remain unchanged
if one of the following occurs.
.Bl -tag -width Er
.It Bq Er EFAULT

4
lib/libc/sys/sigwait.2
View File

@ -27,7 +27,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd September 27, 2012
.Dd September 6, 2013
.Dt SIGWAIT 2
.Os
.Sh NAME
@ -50,7 +50,7 @@ waits until one or more of the selected signals has been generated.
Then
.Fn sigwait
atomically clears one of the selected signals from the set of pending signals
for the process and sets the location pointed to by
(for the process or for the current thread) and sets the location pointed to by
.Fa sig
to the signal number that was cleared.
.Pp