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authorLinus Torvalds <torvalds@linux-foundation.org>2019-04-30 18:41:22 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-04-30 18:41:22 +0300
commitbf3bd966dfd7d9582f50e9bd08b15922197cd277 (patch)
treed1cf495271b06cacd171173493db2b58b6858b8f /Documentation
parentfea27bc7ff43a8beb6bebe6d4fe9eb889e185d4a (diff)
parentc114944d7d67f24e71562fcfc18d550ab787e4d4 (diff)
downloadlinux-bf3bd966dfd7d9582f50e9bd08b15922197cd277.tar.xz
Merge tag 'usb-5.1-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb
Pull USB fixes from Greg KH: "Here are some small USB fixes for a bunch of warnings/errors that the syzbot has been finding with it's new-found ability to stress-test the USB layer. All of these are tiny, but fix real issues, and are marked for stable as well. All of these have had lots of testing in linux-next as well" * tag 'usb-5.1-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: USB: w1 ds2490: Fix bug caused by improper use of altsetting array USB: yurex: Fix protection fault after device removal usb: usbip: fix isoc packet num validation in get_pipe USB: core: Fix bug caused by duplicate interface PM usage counter USB: dummy-hcd: Fix failure to give back unlinked URBs USB: core: Fix unterminated string returned by usb_string()
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/driver-api/usb/power-management.rst14
1 files changed, 9 insertions, 5 deletions
diff --git a/Documentation/driver-api/usb/power-management.rst b/Documentation/driver-api/usb/power-management.rst
index 79beb807996b..4a74cf6f2797 100644
--- a/Documentation/driver-api/usb/power-management.rst
+++ b/Documentation/driver-api/usb/power-management.rst
@@ -370,11 +370,15 @@ autosuspend the interface's device. When the usage counter is = 0
then the interface is considered to be idle, and the kernel may
autosuspend the device.
-Drivers need not be concerned about balancing changes to the usage
-counter; the USB core will undo any remaining "get"s when a driver
-is unbound from its interface. As a corollary, drivers must not call
-any of the ``usb_autopm_*`` functions after their ``disconnect``
-routine has returned.
+Drivers must be careful to balance their overall changes to the usage
+counter. Unbalanced "get"s will remain in effect when a driver is
+unbound from its interface, preventing the device from going into
+runtime suspend should the interface be bound to a driver again. On
+the other hand, drivers are allowed to achieve this balance by calling
+the ``usb_autopm_*`` functions even after their ``disconnect`` routine
+has returned -- say from within a work-queue routine -- provided they
+retain an active reference to the interface (via ``usb_get_intf`` and
+``usb_put_intf``).
Drivers using the async routines are responsible for their own
synchronization and mutual exclusion.