svn commit: r325516 - in head: lib/libc/gen sys/kern

[Bartek Rutkowski]

Author: robak (ports committer)
Date: Tue Nov  7 15:13:32 2017
New Revision: 325516
URL: https://svnweb.freebsd.org/changeset/base/325516

Log:
  Make sysctl_kern_proc_umask execute fast path when requested pid in
  curproc->p_pid or 0, avoiding unnecessary locking. Update libc consumer
  to skip calling getpid().
  
  Submitted by:	Pawel Biernacki <pawel.biernacki at gmail.com>
  Reviewed by:	mjg, robak
  Approved by:	mjg
  Sponsored by:	Mysterious Code Ltd.
  Differential Revision:	D12972

Modified:
  head/lib/libc/gen/setmode.c
  head/sys/kern/kern_proc.c

Modified: head/lib/libc/gen/setmode.c
==============================================================================
--- head/lib/libc/gen/setmode.c	Tue Nov  7 15:01:38 2017	(r325515)
+++ head/lib/libc/gen/setmode.c	Tue Nov  7 15:13:32 2017	(r325516)
@@ -356,7 +356,7 @@ getumask(void)
 	 * security.bsd.unprivileged_proc_debug is set to 0.
 	 */
 	len = sizeof(smask);
-	if (sysctl((int[4]){ CTL_KERN, KERN_PROC, KERN_PROC_UMASK, getpid() },
+	if (sysctl((int[4]){ CTL_KERN, KERN_PROC, KERN_PROC_UMASK, 0 },
 	    4, &smask, &len, NULL, 0) == 0)
 		return (smask);
 

Modified: head/sys/kern/kern_proc.c
==============================================================================
--- head/sys/kern/kern_proc.c	Tue Nov  7 15:01:38 2017	(r325515)
+++ head/sys/kern/kern_proc.c	Tue Nov  7 15:13:32 2017	(r325516)
@@ -2770,18 +2770,25 @@ sysctl_kern_proc_umask(SYSCTL_HANDLER_ARGS)
 	struct proc *p;
 	int error;
 	u_short fd_cmask;
+	pid_t pid;
 
 	if (namelen != 1)
 		return (EINVAL);
 
-	error = pget((pid_t)name[0], PGET_WANTREAD, &p);
+	pid = (pid_t)name[0];
+	p = curproc;
+	if (pid == p->p_pid || pid == 0) {
+		fd_cmask = p->p_fd->fd_cmask;
+		goto out;
+	}
+
+	error = pget(pid, PGET_WANTREAD, &p);
 	if (error != 0)
 		return (error);
 
-	FILEDESC_SLOCK(p->p_fd);
 	fd_cmask = p->p_fd->fd_cmask;
-	FILEDESC_SUNLOCK(p->p_fd);
 	PRELE(p);
+out:
 	error = SYSCTL_OUT(req, &fd_cmask, sizeof(fd_cmask));
 	return (error);
 }