Attachment 183542 Details for Bug 219701 – Proposed patch to cache the periph_driver pointer.

Proposed patch to cache the periph_driver pointer.

cam_periph_drv.20170616.1.txt (text/plain), 1.37 KB, created by Kenneth D. Merry on 2017-06-16 18:39:03 UTC

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Creator: Kenneth D. Merry

Created: 2017-06-16 18:39:03 UTC

Size: 1.37 KB

patch

obsolete

>--- //depot/users/kenm/FreeBSD-test/sys/cam/cam_periph.c	2017-06-14 18:49:32.000000000 -0600
>+++ /usr/home/kenm/perforce4/kenm/FreeBSD-test/sys/cam/cam_periph.c	2017-06-14 18:49:32.000000000 -0600
>--- /tmp/tmp.6403.79	2017-06-16 12:36:41.000000000 -0600
>+++ /usr/home/kenm/perforce4/kenm/FreeBSD-test/sys/cam/cam_periph.c	2017-06-16 12:36:22.288576278 -0600
>@@ -661,6 +661,7 @@
> camperiphfree(struct cam_periph *periph)
> {
> 	struct periph_driver **p_drv;
>+	struct periph_driver *drv;
> 
> 	cam_periph_assert(periph, MA_OWNED);
> 	KASSERT(periph->periph_allocating == 0, ("%s%d: freed while allocating",
>@@ -673,6 +674,15 @@
> 		printf("camperiphfree: attempt to free non-existant periph\n");
> 		return;
> 	}
>+	/*
>+	 * Cache a pointer to the periph_driver structure.  If a
>+	 * periph_driver is added or removed from the array (see
>+	 * periphdriver_register()) while we drop the toplogy lock
>+	 * below, p_drv may change.  This doesn't protect against this
>+	 * particular periph_driver going away.  That will require full
>+	 * reference counting in the periph_driver infrastructure.
>+	 */
>+	drv = *p_drv;
> 
> 	/*
> 	 * We need to set this flag before dropping the topology lock, to
>@@ -708,8 +718,8 @@
> 	 */
> 	xpt_lock_buses();
> 
>-	TAILQ_REMOVE(&(*p_drv)->units, periph, unit_links);
>-	(*p_drv)->generation++;
>+	TAILQ_REMOVE(&drv->units, periph, unit_links);
>+	drv->generation++;
> 
> 	xpt_remove_periph(periph);
>

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Attachments on bug 219701: 183542