Introduce no_poll() default method for device drivers. Have it

do exactly the same as vop_nopoll() for consistency and put a
comment in the two pointing at each other.

Retire seltrue() in favour of no_poll().

Create private default functions in kern_conf.c instead of public
ones.

Change default strategy to return the bio with ENODEV instead of
doing nothing which would lead the bio stranded.

Retire public nullopen() and nullclose() as well as the entire band
of public no{read,write,ioctl,mmap,kqfilter,strategy,poll,dump}
funtions, they are the default actions now.

Move the final two trivial functions from subr_xxx.c to kern_conf.c
and retire the now empty subr_xxx.c

1 files changed, 75 insertions, 14 deletions

diff --git a/sys/kern/kern_conf.c b/sys/kern/kern_conf.c
index 56eaf11..d578077 100644
--- a/sys/kern/kern_conf.c
+++ b/sys/kern/kern_conf.c
@@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/conf.h>
 #include <sys/vnode.h>
 #include <sys/queue.h>
+#include <sys/poll.h>
 #include <sys/ctype.h>
 #include <machine/stdarg.h>
 
@@ -68,7 +69,19 @@ static int ready_for_devs;
 static int free_devt;
 SYSCTL_INT(_debug, OID_AUTO, free_devt, CTLFLAG_RW, &free_devt, 0, "");
 
-/* Define a dead_cdevsw for use when devices leave unexpectedly. */
+int
+nullop(void)
+{
+
+	return (0);
+}
+
+int
+eopnotsupp(void)
+{
+
+	return (EOPNOTSUPP);
+}
 
 static int
 enxio(void)
@@ -76,13 +89,21 @@ enxio(void)
 	return (ENXIO);
 }
 
+static int
+enodev(void)
+{
+	return (ENODEV);
+}
+
+/* Define a dead_cdevsw for use when devices leave unexpectedly. */
+
 #define dead_open	(d_open_t *)enxio
 #define dead_close	(d_close_t *)enxio
 #define dead_read	(d_read_t *)enxio
 #define dead_write	(d_write_t *)enxio
 #define dead_ioctl	(d_ioctl_t *)enxio
-#define dead_poll	nopoll
-#define dead_mmap	nommap
+#define dead_poll	(d_poll_t *)enodev
+#define dead_mmap	(d_mmap_t *)enodev
 
 static void
 dead_strategy(struct bio *bp)
@@ -92,7 +113,6 @@ dead_strategy(struct bio *bp)
 }
 
 #define dead_dump	(dumper_t *)enxio
-
 #define dead_kqfilter	(d_kqfilter_t *)enxio
 
 static struct cdevsw dead_cdevsw = {
@@ -110,6 +130,47 @@ static struct cdevsw dead_cdevsw = {
 	.d_kqfilter =	dead_kqfilter
 };
 
+/* Default methods if driver does not specify method */
+
+#define null_open	(d_open_t *)nullop
+#define null_close	(d_close_t *)nullop
+#define no_read		(d_read_t *)enodev
+#define no_write	(d_write_t *)enodev
+#define no_ioctl	(d_ioctl_t *)enodev
+#define no_mmap		(d_mmap_t *)enodev
+
+static int
+no_kqfilter(dev_t dev __unused, struct knote *kn __unused)
+{
+
+	return (1);
+}
+
+static void
+no_strategy(struct bio *bp)
+{
+
+	biofinish(bp, NULL, ENODEV);
+}
+
+static int
+no_poll(dev_t dev __unused, int events, struct thread *td __unused)
+{
+	/*
+	 * Return true for read/write.  If the user asked for something
+	 * special, return POLLNVAL, so that clients have a way of
+	 * determining reliably whether or not the extended
+	 * functionality is present without hard-coding knowledge
+	 * of specific filesystem implementations.
+	 * Stay in sync with vop_nopoll().
+	 */
+	if (events & ~POLLSTANDARD)
+		return (POLLNVAL);
+
+	return (events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
+}
+
+#define no_dump		(dumper_t *)enodev
 
 struct cdevsw *
 devsw(dev_t dev)
@@ -276,16 +337,16 @@ make_dev(struct cdevsw *devsw, int minor, uid_t uid, gid_t gid, int perms, const
 	KASSERT((minor & ~0xffff00ff) == 0,
 	    ("Invalid minor (0x%x) in make_dev", minor));
 
-	if (devsw->d_open == NULL)	devsw->d_open = nullopen;
-	if (devsw->d_close == NULL)	devsw->d_close = nullclose;
-	if (devsw->d_read == NULL)	devsw->d_read = noread;
-	if (devsw->d_write == NULL)	devsw->d_write = nowrite;
-	if (devsw->d_ioctl == NULL)	devsw->d_ioctl = noioctl;
-	if (devsw->d_poll == NULL)	devsw->d_poll = nopoll;
-	if (devsw->d_mmap == NULL)	devsw->d_mmap = nommap;
-	if (devsw->d_strategy == NULL)	devsw->d_strategy = nostrategy;
-	if (devsw->d_dump == NULL)	devsw->d_dump = nodump;
-	if (devsw->d_kqfilter == NULL)	devsw->d_kqfilter = nokqfilter;
+	if (devsw->d_open == NULL)	devsw->d_open = null_open;
+	if (devsw->d_close == NULL)	devsw->d_close = null_close;
+	if (devsw->d_read == NULL)	devsw->d_read = no_read;
+	if (devsw->d_write == NULL)	devsw->d_write = no_write;
+	if (devsw->d_ioctl == NULL)	devsw->d_ioctl = no_ioctl;
+	if (devsw->d_poll == NULL)	devsw->d_poll = no_poll;
+	if (devsw->d_mmap == NULL)	devsw->d_mmap = no_mmap;
+	if (devsw->d_strategy == NULL)	devsw->d_strategy = no_strategy;
+	if (devsw->d_dump == NULL)	devsw->d_dump = no_dump;
+	if (devsw->d_kqfilter == NULL)	devsw->d_kqfilter = no_kqfilter;
 
 	if (devsw->d_maj == MAJOR_AUTO) {
 		for (i = NUMCDEVSW - 1; i > 0; i--)