svn commit: r366550 - head/sys/kern

[Konstantin Belousov]

Author: kib
Date: Thu Oct  8 22:34:34 2020
New Revision: 366550
URL: https://svnweb.freebsd.org/changeset/base/366550

Log:
  sig_intr(9): return early if AST is not scheduled.
  
  Check td_flags for relevant AST requests lock-less.  This opens the
  race slightly wider where sig_intr() returns false negative, but might
  be it is worth it.
  
  Requested by:	mjg
  Sponsored by:	The FreeBSD Foundation
  MFC after:	1 week

Modified:
  head/sys/kern/kern_sig.c

Modified: head/sys/kern/kern_sig.c
==============================================================================
--- head/sys/kern/kern_sig.c	Thu Oct  8 22:31:11 2020	(r366549)
+++ head/sys/kern/kern_sig.c	Thu Oct  8 22:34:34 2020	(r366550)
@@ -3212,6 +3212,9 @@ sig_intr(void)
 	int ret;
 
 	td = curthread;
+	if ((td->td_flags & (TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK)) == 0)
+		return (0);
+
 	p = td->td_proc;
 
 	PROC_LOCK(p);