linux-kernel - Re: parent process behaviour to signal after vfork()

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Message-ID: <cfd18e0f0810300626k21a10b22y9f8ead75c02f7782@mail.gmail.com>
Date:	Thu, 30 Oct 2008 08:26:50 -0500
From:	"Michael Kerrisk" <mtk.manpages@...glemail.com>
To:	Valdis.Kletnieks@...edu
Cc:	"Halesh S" <halesh.s@...ia.com>, linux-kernel@...r.kernel.org
Subject: Re: parent process behaviour to signal after vfork()

Oops -- forgot the patch.  Here it is:

--- a/man2/vfork.2
+++ b/man2/vfork.2
@@ -80,13 +80,15 @@ where a child will be created which then
immediately issues an
 .BR vfork ()
 differs from
 .BR fork (2)
-in that the parent is suspended until the child makes a call to
-.BR execve (2)
-or
-.BR _exit (2).
-The child shares all memory with its parent, including the stack, until
-.BR execve (2)
-is issued by the child.
+in that the parent is suspended until the child terminates
+(either normally,
+by calling
+.BR exit (2),
+or abnormally, after delivery of a fatal signal),
+or it makes a call to
+.BR execve (2).
+Until that point, the child shares all memory with its parent,
+including the stack.
 The child must not return from the current function or call
 .BR exit (3),
 but may call
@@ -95,9 +97,8 @@ but may call
 Signal handlers are inherited, but not shared.
 Signals to the parent
 arrive after the child releases the parent's memory
-(i.e., after the child calls
-.BR _exit (2)
-or
+(i.e., after the child terminates
+or calls
 .BR execve (2)).
 .SS "Historic Description"
 Under Linux,
@@ -135,11 +136,9 @@ The requirements put on
 by the standards are weaker than those put on
 .BR fork (2),
 so an implementation where the two are synonymous is compliant.
-In particular, the programmer cannot
-rely on the parent remaining blocked until a call of
-.BR execve (2)
-or
-.BR _exit (2)
+In particular, the programmer cannot rely on the parent
+remaining blocked until the child either terminates or calls
+.BR execve (2),
 and cannot rely on any specific behavior with respect to shared memory.
 .\" In AIXv3.1 vfork is equivalent to fork.
 .SH NOTES
--
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