Revision 24f531371de17010f2b1b57d90e42240032e7733 authored by Alan Stern on 07 August 2013, 14:58:05 UTC, committed by Greg Kroah-Hartman on 12 August 2013, 20:45:26 UTC
Since commits 4005ad4390bf (EHCI: implement new semantics for URB_ISO_ASAP) and c75c5ab575af (ALSA: USB: adjust for changed 3.8 USB API) became widely distributed, people have been experiencing problems with audio transfers. The slightest underrun causes complete failure, requiring the audio stream to be restarted. It turns out that the current isochronous API doesn't handle underruns in the best way. The ALSA developers would much rather have transfers that are submitted too late be accepted and complete in the normal fashion, rather than being refused outright. This patch implements the requested approach. When an isochronous URB submission is so late that all its scheduled slots have already expired, a debugging message will be printed in the log and the URB will be accepted as usual. Assuming it was submitted by a completion handler (which is normally the case), it will complete shortly thereafter with all the usb_iso_packet_descriptor status fields marked -EXDEV. This fixes (for ehci-hcd) https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1191603 It should be applied to all kernels that include commit 4005ad4390bf. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Tested-by: Maksim Boyko <maksboyko@yandex.ru> CC: Clemens Ladisch <clemens@ladisch.de> CC: <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Kbuild
#
# Kbuild for top-level directory of the kernel
# This file takes care of the following:
# 1) Generate bounds.h
# 2) Generate asm-offsets.h (may need bounds.h)
# 3) Check for missing system calls
#####
# 1) Generate bounds.h
bounds-file := include/generated/bounds.h
always := $(bounds-file)
targets := $(bounds-file) kernel/bounds.s
quiet_cmd_bounds = GEN $@
define cmd_bounds
(set -e; \
echo "#ifndef __LINUX_BOUNDS_H__"; \
echo "#define __LINUX_BOUNDS_H__"; \
echo "/*"; \
echo " * DO NOT MODIFY."; \
echo " *"; \
echo " * This file was generated by Kbuild"; \
echo " *"; \
echo " */"; \
echo ""; \
sed -ne $(sed-y) $<; \
echo ""; \
echo "#endif" ) > $@
endef
# We use internal kbuild rules to avoid the "is up to date" message from make
kernel/bounds.s: kernel/bounds.c FORCE
$(Q)mkdir -p $(dir $@)
$(call if_changed_dep,cc_s_c)
$(obj)/$(bounds-file): kernel/bounds.s Kbuild
$(Q)mkdir -p $(dir $@)
$(call cmd,bounds)
#####
# 2) Generate asm-offsets.h
#
offsets-file := include/generated/asm-offsets.h
always += $(offsets-file)
targets += $(offsets-file)
targets += arch/$(SRCARCH)/kernel/asm-offsets.s
# Default sed regexp - multiline due to syntax constraints
define sed-y
"/^->/{s:->#\(.*\):/* \1 */:; \
s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
s:->::; p;}"
endef
quiet_cmd_offsets = GEN $@
define cmd_offsets
(set -e; \
echo "#ifndef __ASM_OFFSETS_H__"; \
echo "#define __ASM_OFFSETS_H__"; \
echo "/*"; \
echo " * DO NOT MODIFY."; \
echo " *"; \
echo " * This file was generated by Kbuild"; \
echo " *"; \
echo " */"; \
echo ""; \
sed -ne $(sed-y) $<; \
echo ""; \
echo "#endif" ) > $@
endef
# We use internal kbuild rules to avoid the "is up to date" message from make
arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
$(obj)/$(bounds-file) FORCE
$(Q)mkdir -p $(dir $@)
$(call if_changed_dep,cc_s_c)
$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
$(call cmd,offsets)
#####
# 3) Check for missing system calls
#
always += missing-syscalls
targets += missing-syscalls
quiet_cmd_syscalls = CALL $<
cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags)
missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
$(call cmd,syscalls)
# Keep these two files during make clean
no-clean-files := $(bounds-file) $(offsets-file)
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