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authorAlan Stern <stern@rowland.harvard.edu>2011-03-07 11:11:52 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2011-03-23 13:03:51 -0700
commitca81d7760eb900e6f42b60e52b8a3efc88780e37 (patch)
tree6cfc89ec36270cbadb3d944f95bac63f844ba44a /include
parenta6b2dd27d8d97c83b7f0c70c8813f96801f85c00 (diff)
downloadlinux-2.6.38-lt-ux500-ca81d7760eb900e6f42b60e52b8a3efc88780e37.tar.gz
USB: move usbcore away from hcd->state
commit 9b37596a2e860404503a3f2a6513db60c296bfdc upstream. The hcd->state variable is a disaster. It's not clearly owned by either usbcore or the host controller drivers, and they both change it from time to time, potentially stepping on each other's toes. It's not protected by any locks. And there's no mechanism to prevent it from going through an invalid transition. This patch (as1451) takes a first step toward fixing these problems. As it turns out, usbcore uses hcd->state for essentially only two things: checking whether the controller's root hub is running and checking whether the controller has died. Therefore the patch adds two new atomic bitflags to the hcd structure, to store these pieces of information. The new flags are used only by usbcore, and a private spinlock prevents invalid combinations (a dead controller's root hub cannot be running). The patch does not change the places where usbcore sets hcd->state, since HCDs may depend on them. Furthermore, there is one place in usb_hcd_irq() where usbcore still must use hcd->state: An HCD's interrupt handler can implicitly indicate that the controller died by setting hcd->state to HC_STATE_HALT. Nevertheless, the new code is a big improvement over the current code. The patch makes one other change. The hcd_bus_suspend() and hcd_bus_resume() routines now check first whether the host controller has died; if it has then they return immediately without calling the HCD's bus_suspend or bus_resume methods. This fixes the major problem reported in Bugzilla #29902: The system fails to suspend after a host controller dies during system resume. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Tested-by: Alex Terekhov <a.terekhov@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include')
-rw-r--r--include/linux/usb/hcd.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index a854fe89484..f21f5996fa6 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -99,6 +99,8 @@ struct usb_hcd {
#define HCD_FLAG_POLL_RH 2 /* poll for rh status? */
#define HCD_FLAG_POLL_PENDING 3 /* status has changed? */
#define HCD_FLAG_WAKEUP_PENDING 4 /* root hub is resuming? */
+#define HCD_FLAG_RH_RUNNING 5 /* root hub is running? */
+#define HCD_FLAG_DEAD 6 /* controller has died? */
/* The flags can be tested using these macros; they are likely to
* be slightly faster than test_bit().
@@ -108,6 +110,8 @@ struct usb_hcd {
#define HCD_POLL_RH(hcd) ((hcd)->flags & (1U << HCD_FLAG_POLL_RH))
#define HCD_POLL_PENDING(hcd) ((hcd)->flags & (1U << HCD_FLAG_POLL_PENDING))
#define HCD_WAKEUP_PENDING(hcd) ((hcd)->flags & (1U << HCD_FLAG_WAKEUP_PENDING))
+#define HCD_RH_RUNNING(hcd) ((hcd)->flags & (1U << HCD_FLAG_RH_RUNNING))
+#define HCD_DEAD(hcd) ((hcd)->flags & (1U << HCD_FLAG_DEAD))
/* Flags that get set only during HCD registration or removal. */
unsigned rh_registered:1;/* is root hub registered? */