svn commit: r207729 - in head/sys: fs/devfs kern sys

Konstantin Belousov kib at FreeBSD.org
Thu May 6 19:22:50 UTC 2010


Author: kib
Date: Thu May  6 19:22:50 2010
New Revision: 207729
URL: http://svn.freebsd.org/changeset/base/207729

Log:
  Add MAKEDEV_NOWAIT flag to make_dev_credf(9), to create a device node
  in a no-sleep context. If resource allocation cannot be done without
  sleep, make_dev_credf() fails and returns NULL.
  
  Reviewed by:	jh
  MFC after:	2 weeks

Modified:
  head/sys/fs/devfs/devfs_devs.c
  head/sys/fs/devfs/devfs_int.h
  head/sys/kern/kern_conf.c
  head/sys/sys/conf.h

Modified: head/sys/fs/devfs/devfs_devs.c
==============================================================================
--- head/sys/fs/devfs/devfs_devs.c	Thu May  6 18:58:32 2010	(r207728)
+++ head/sys/fs/devfs/devfs_devs.c	Thu May  6 19:22:50 2010	(r207729)
@@ -115,17 +115,21 @@ SYSCTL_INT(_debug_sizeof, OID_AUTO, cdev
     0, sizeof(struct cdev_priv), "sizeof(struct cdev_priv)");
 
 struct cdev *
-devfs_alloc(void)
+devfs_alloc(int flags)
 {
 	struct cdev_priv *cdp;
 	struct cdev *cdev;
 	struct timespec ts;
 
-	cdp = malloc(sizeof *cdp, M_CDEVP, M_USE_RESERVE | M_ZERO | M_WAITOK);
+	cdp = malloc(sizeof *cdp, M_CDEVP, M_USE_RESERVE | M_ZERO |
+	    ((flags & MAKEDEV_NOWAIT) ? M_NOWAIT : M_WAITOK));
+	if (cdp == NULL)
+		return (NULL);
 
 	cdp->cdp_dirents = &cdp->cdp_dirent0;
 	cdp->cdp_dirent0 = NULL;
 	cdp->cdp_maxdirent = 0;
+	cdp->cdp_inode = 0;
 
 	cdev = &cdp->cdp_c;
 
@@ -133,6 +137,7 @@ devfs_alloc(void)
 	LIST_INIT(&cdev->si_children);
 	vfs_timestamp(&ts);
 	cdev->si_atime = cdev->si_mtime = cdev->si_ctime = ts;
+	cdev->si_cred = NULL;
 
 	return (cdev);
 }

Modified: head/sys/fs/devfs/devfs_int.h
==============================================================================
--- head/sys/fs/devfs/devfs_int.h	Thu May  6 18:58:32 2010	(r207728)
+++ head/sys/fs/devfs/devfs_int.h	Thu May  6 19:22:50 2010	(r207729)
@@ -70,7 +70,7 @@ struct cdev_priv {
 
 #define	cdev2priv(c)	member2struct(cdev_priv, cdp_c, c)
 
-struct cdev *devfs_alloc(void);
+struct cdev *devfs_alloc(int);
 void devfs_free(struct cdev *);
 void devfs_create(struct cdev *dev);
 void devfs_destroy(struct cdev *dev);

Modified: head/sys/kern/kern_conf.c
==============================================================================
--- head/sys/kern/kern_conf.c	Thu May  6 18:58:32 2010	(r207728)
+++ head/sys/kern/kern_conf.c	Thu May  6 19:22:50 2010	(r207729)
@@ -505,7 +505,7 @@ giant_mmap_single(struct cdev *dev, vm_o
 }
 
 static void
-notify(struct cdev *dev, const char *ev)
+notify(struct cdev *dev, const char *ev, int flags)
 {
 	static const char prefix[] = "cdev=";
 	char *data;
@@ -514,7 +514,8 @@ notify(struct cdev *dev, const char *ev)
 	if (cold)
 		return;
 	namelen = strlen(dev->si_name);
-	data = malloc(namelen + sizeof(prefix), M_TEMP, M_NOWAIT);
+	data = malloc(namelen + sizeof(prefix), M_TEMP,
+	     (flags & MAKEDEV_NOWAIT) ? M_NOWAIT : M_WAITOK);
 	if (data == NULL)
 		return;
 	memcpy(data, prefix, sizeof(prefix) - 1);
@@ -524,17 +525,17 @@ notify(struct cdev *dev, const char *ev)
 }
 
 static void
-notify_create(struct cdev *dev)
+notify_create(struct cdev *dev, int flags)
 {
 
-	notify(dev, "CREATE");
+	notify(dev, "CREATE", flags);
 }
 
 static void
 notify_destroy(struct cdev *dev)
 {
 
-	notify(dev, "DESTROY");
+	notify(dev, "DESTROY", MAKEDEV_WAITOK);
 }
 
 static struct cdev *
@@ -572,24 +573,27 @@ fini_cdevsw(struct cdevsw *devsw)
 	devsw->d_flags &= ~D_INIT;
 }
 
-static void
-prep_cdevsw(struct cdevsw *devsw)
+static int
+prep_cdevsw(struct cdevsw *devsw, int flags)
 {
 	struct cdevsw *dsw2;
 
 	mtx_assert(&devmtx, MA_OWNED);
 	if (devsw->d_flags & D_INIT)
-		return;
+		return (1);
 	if (devsw->d_flags & D_NEEDGIANT) {
 		dev_unlock();
-		dsw2 = malloc(sizeof *dsw2, M_DEVT, M_WAITOK);
+		dsw2 = malloc(sizeof *dsw2, M_DEVT,
+		     (flags & MAKEDEV_NOWAIT) ? M_NOWAIT : M_WAITOK);
 		dev_lock();
+		if (dsw2 == NULL && !(devsw->d_flags & D_INIT))
+			return (0);
 	} else
 		dsw2 = NULL;
 	if (devsw->d_flags & D_INIT) {
 		if (dsw2 != NULL)
 			cdevsw_free_devlocked(dsw2);
-		return;
+		return (1);
 	}
 
 	if (devsw->d_version != D_VERSION_03) {
@@ -647,6 +651,7 @@ prep_cdevsw(struct cdevsw *devsw)
 
 	if (dsw2 != NULL)
 		cdevsw_free_devlocked(dsw2);
+	return (1);
 }
 
 static struct cdev *
@@ -657,9 +662,15 @@ make_dev_credv(int flags, struct cdevsw 
 	struct cdev *dev;
 	int i;
 
-	dev = devfs_alloc();
+	dev = devfs_alloc(flags);
+	if (dev == NULL)
+		return (NULL);
 	dev_lock();
-	prep_cdevsw(devsw);
+	if (!prep_cdevsw(devsw, flags)) {
+		dev_unlock();
+		devfs_free(dev);
+		return (NULL);
+	}
 	dev = newdev(devsw, unit, dev);
 	if (flags & MAKEDEV_REF)
 		dev_refl(dev);
@@ -686,8 +697,6 @@ make_dev_credv(int flags, struct cdevsw 
 	dev->si_flags |= SI_NAMED;
 	if (cr != NULL)
 		dev->si_cred = crhold(cr);
-	else
-		dev->si_cred = NULL;
 	dev->si_uid = uid;
 	dev->si_gid = gid;
 	dev->si_mode = mode;
@@ -696,7 +705,7 @@ make_dev_credv(int flags, struct cdevsw 
 	clean_unrhdrl(devfs_inos);
 	dev_unlock_and_free();
 
-	notify_create(dev);
+	notify_create(dev, flags);
 
 	return (dev);
 }
@@ -771,7 +780,7 @@ make_dev_alias(struct cdev *pdev, const 
 	int i;
 
 	KASSERT(pdev != NULL, ("NULL pdev"));
-	dev = devfs_alloc();
+	dev = devfs_alloc(MAKEDEV_WAITOK);
 	dev_lock();
 	dev->si_flags |= SI_ALIAS;
 	dev->si_flags |= SI_NAMED;
@@ -788,7 +797,7 @@ make_dev_alias(struct cdev *pdev, const 
 	clean_unrhdrl(devfs_inos);
 	dev_unlock();
 
-	notify_create(dev);
+	notify_create(dev, MAKEDEV_WAITOK);
 
 	return (dev);
 }
@@ -973,9 +982,9 @@ clone_create(struct clonedevs **cdp, str
 	 *       the end of the list.
 	 */
 	unit = *up;
-	ndev = devfs_alloc();
+	ndev = devfs_alloc(MAKEDEV_WAITOK);
 	dev_lock();
-	prep_cdevsw(csw);
+	prep_cdevsw(csw, MAKEDEV_WAITOK);
 	low = extra;
 	de = dl = NULL;
 	cd = *cdp;

Modified: head/sys/sys/conf.h
==============================================================================
--- head/sys/sys/conf.h	Thu May  6 18:58:32 2010	(r207728)
+++ head/sys/sys/conf.h	Thu May  6 19:22:50 2010	(r207729)
@@ -262,8 +262,10 @@ struct cdev *make_dev(struct cdevsw *_de
 struct cdev *make_dev_cred(struct cdevsw *_devsw, int _unit,
 		struct ucred *_cr, uid_t _uid, gid_t _gid, int _perms,
 		const char *_fmt, ...) __printflike(7, 8);
-#define MAKEDEV_REF     0x1
-#define MAKEDEV_WHTOUT	0x2
+#define	MAKEDEV_REF     0x1
+#define	MAKEDEV_WHTOUT	0x2
+#define	MAKEDEV_NOWAIT	0x4
+#define	MAKEDEV_WAITOK	0x8
 struct cdev *make_dev_credf(int _flags,
 		struct cdevsw *_devsw, int _unit,
 		struct ucred *_cr, uid_t _uid, gid_t _gid, int _mode,


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