https://github.com/torvalds/linux
Revision 8dab63761219d7bc6a7d7d3b5f0fca76af5533a5 authored by Jeremy Kerr on 11 January 2008, 13:28:04 UTC, committed by Linus Torvalds on 11 January 2008, 19:47:43 UTC
Since the introduction of the acquire_console_sem calls in 0333d83509c7d8496c8965b5ba9bc0c98e83c259, kexecing can cause the kernel to deadlock: ps3fb_shutdown() -> unregister_framebuffer() -> fb_notifier_call_chain(FB_EVENT_FB_UNBIND) -> fbcon_fb_unbind() -> unbind_con_driver() -> bind_con_driver() [ acquires console_sem ] -> fbcon_deinit() -> fbops->fb_release(newinfo, 0) -> ps3fb_release() -> ps3fb_sync() [ acquires console_sem ] This change avoids the deadlock by moving the acquire_console_sem() out of ps3fb_sync(), and puts it into the two other callsites, leaving ps3fb_release() to call ps3fb_sync() without the console semaphore. [Geert] - Corrected call sequence above - ps3fb_release() may be called with and without console_sem held. This is an inconsistency that should be fixed at the fb level, but for now, try to acquire console_sem in ps3fb_release(). I think it's safer to let ps3fb_release() try to acquire console_sem and not refresh the screen if it fails, than to call ps3fb_sync() without holding console_sem, as ps3fb_par may be modified at the same time, causing crashes or lockups. Besides, ps3fb_release() only calls ps3fb_sync() to refresh the screen when display flipping is disabled, which is an uncommon case (except during shutdown/kexec). Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent ba21611
Tip revision: 8dab63761219d7bc6a7d7d3b5f0fca76af5533a5 authored by Jeremy Kerr on 11 January 2008, 13:28:04 UTC
ps3fb: fix deadlock on kexec()
ps3fb: fix deadlock on kexec()
Tip revision: 8dab637
Kbuild
#
# Kbuild for top-level directory of the kernel
# This file takes care of the following:
# 1) Generate asm-offsets.h
# 2) Check for missing system calls
#####
# 1) Generate asm-offsets.h
#
offsets-file := include/asm-$(SRCARCH)/asm-offsets.h
always := $(offsets-file)
targets := $(offsets-file)
targets += arch/$(SRCARCH)/kernel/asm-offsets.s
clean-files := $(addprefix $(objtree)/,$(targets))
# Default sed regexp - multiline due to syntax constraints
define sed-y
"/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"
endef
# Override default regexp for specific architectures
sed-$(CONFIG_MIPS) := "/^@@@/{s/^@@@//; s/ \#.*\$$//; p;}"
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 FORCE
$(Q)mkdir -p $(dir $@)
$(call if_changed_dep,cc_s_c)
$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
$(Q)mkdir -p $(dir $@)
$(call cmd,offsets)
#####
# 2) Check for missing system calls
#
quiet_cmd_syscalls = CALL $<
cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags)
PHONY += missing-syscalls
missing-syscalls: scripts/checksyscalls.sh FORCE
$(call cmd,syscalls)
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