svn commit: r339786 - head/sys/kern

[Conrad Meyer]

Author: cem
Date: Fri Oct 26 20:07:46 2018
New Revision: 339786
URL: https://svnweb.freebsd.org/changeset/base/339786

Log:
  poll: Unify userspace pollfd pointer name
  
  Some of the poll code used 'fds' and some used 'ufds' to refer to the
  uap->fds userspace pointer that was passed around to subroutines.  Some of
  the poll code used 'fds' to refer to the kernel memory pollfd arrays, which
  seemed unnecessarily confusing.
  
  Unify on 'ufds' to refer to the userspace pollfd array.
  
  Additionally, 'bits' is not an accurate description of the kernel pollfd
  array in kern_poll, so rename that to 'kfds'.  Finally, clean up some logic
  with mallocarray() and nitems().
  
  No functional change.
  
  Reviewed by:	markj
  Differential Revision:	https://reviews.freebsd.org/D17670

Modified:
  head/sys/kern/sys_generic.c

Modified: head/sys/kern/sys_generic.c
==============================================================================
--- head/sys/kern/sys_generic.c	Fri Oct 26 20:03:59 2018	(r339785)
+++ head/sys/kern/sys_generic.c	Fri Oct 26 20:07:46 2018	(r339786)
@@ -1304,16 +1304,15 @@ sys_poll(struct thread *td, struct poll_args *uap)
 }
 
 int
-kern_poll(struct thread *td, struct pollfd *fds, u_int nfds,
+kern_poll(struct thread *td, struct pollfd *ufds, u_int nfds,
     struct timespec *tsp, sigset_t *uset)
 {
-	struct pollfd *bits;
-	struct pollfd smallbits[32];
+	struct pollfd *kfds;
+	struct pollfd stackfds[32];
 	sbintime_t sbt, precision, tmp;
 	time_t over;
 	struct timespec ts;
 	int error;
-	size_t ni;
 
 	precision = 0;
 	if (tsp != NULL) {
@@ -1342,12 +1341,11 @@ kern_poll(struct thread *td, struct pollfd *fds, u_int
 
 	if (nfds > maxfilesperproc && nfds > FD_SETSIZE) 
 		return (EINVAL);
-	ni = nfds * sizeof(struct pollfd);
-	if (ni > sizeof(smallbits))
-		bits = malloc(ni, M_TEMP, M_WAITOK);
+	if (nfds > nitems(stackfds))
+		kfds = mallocarray(nfds, sizeof(*kfds), M_TEMP, M_WAITOK);
 	else
-		bits = smallbits;
-	error = copyin(fds, bits, ni);
+		kfds = stackfds;
+	error = copyin(ufds, kfds, nfds * sizeof(*kfds));
 	if (error)
 		goto done;
 
@@ -1370,7 +1368,7 @@ kern_poll(struct thread *td, struct pollfd *fds, u_int
 	seltdinit(td);
 	/* Iterate until the timeout expires or descriptors become ready. */
 	for (;;) {
-		error = pollscan(td, bits, nfds);
+		error = pollscan(td, kfds, nfds);
 		if (error || td->td_retval[0] != 0)
 			break;
 		error = seltdwait(td, sbt, precision);
@@ -1389,13 +1387,13 @@ done:
 	if (error == EWOULDBLOCK)
 		error = 0;
 	if (error == 0) {
-		error = pollout(td, bits, fds, nfds);
+		error = pollout(td, kfds, ufds, nfds);
 		if (error)
 			goto out;
 	}
 out:
-	if (ni > sizeof(smallbits))
-		free(bits, M_TEMP);
+	if (nfds > nitems(stackfds))
+		free(kfds, M_TEMP);
 	return (error);
 }