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-rw-r--r--Documentation/usb/URB.txt21
1 files changed, 10 insertions, 11 deletions
diff --git a/Documentation/usb/URB.txt b/Documentation/usb/URB.txt
index 00d2c644068e..50da0d455444 100644
--- a/Documentation/usb/URB.txt
+++ b/Documentation/usb/URB.txt
@@ -195,13 +195,12 @@ by the completion handler.
The handler is of the following type:
- typedef void (*usb_complete_t)(struct urb *, struct pt_regs *)
+ typedef void (*usb_complete_t)(struct urb *)
-I.e., it gets the URB that caused the completion call, plus the
-register values at the time of the corresponding interrupt (if any).
-In the completion handler, you should have a look at urb->status to
-detect any USB errors. Since the context parameter is included in the URB,
-you can pass information to the completion handler.
+I.e., it gets the URB that caused the completion call. In the completion
+handler, you should have a look at urb->status to detect any USB errors.
+Since the context parameter is included in the URB, you can pass
+information to the completion handler.
Note that even when an error (or unlink) is reported, data may have been
transferred. That's because USB transfers are packetized; it might take
@@ -210,12 +209,12 @@ have transferred successfully before the completion was called.
NOTE: ***** WARNING *****
-NEVER SLEEP IN A COMPLETION HANDLER. These are normally called
-during hardware interrupt processing. If you can, defer substantial
-work to a tasklet (bottom half) to keep system latencies low. You'll
-probably need to use spinlocks to protect data structures you manipulate
-in completion handlers.
+NEVER SLEEP IN A COMPLETION HANDLER. These are often called in atomic
+context.
+In the current kernel, completion handlers run with local interrupts
+disabled, but in the future this will be changed, so don't assume that
+local IRQs are always disabled inside completion handlers.
1.8. How to do isochronous (ISO) transfers?