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

1 files changed, 11 insertions, 13 deletions

diff --git a/sys/kern/sys_generic.c b/sys/kern/sys_generic.c
index 455220c36752..0e8e173654c5 100644
--- a/sys/kern/sys_generic.c
+++ b/sys/kern/sys_generic.c
@@ -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 nfds,
 
 	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 nfds,
 	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);
 }