###
# Main build makefile.
#
#  Lots of this code have been borrowed or heavily inspired from parts
#  of kbuild code, which is not credited, but mostly developed by:
#
#  Copyright (C) Sam Ravnborg <sam@mars.ravnborg.org>, 2015
#  Copyright (C) Linus Torvalds <torvalds@linux-foundation.org>, 2015
#

PHONY := __build
__build:

ifeq ($(V),1)
  quiet =
  Q =
else
  quiet=quiet_
  Q=@
endif

build-dir := $(srctree)/tools/build

# Define $(fixdep) for dep-cmd function
ifeq ($(OUTPUT),)
  fixdep := $(build-dir)/fixdep
else
  fixdep := $(OUTPUT)/fixdep
endif

# Generic definitions
include $(build-dir)/Build.include

# do not force detected configuration
-include $(OUTPUT).config-detected

# Init all relevant variables used in build files so
# 1) they have correct type
# 2) they do not inherit any value from the environment
subdir-y     :=
obj-y        :=
subdir-y     :=
subdir-obj-y :=

# Build definitions
build-file := $(dir)/Build
-include $(build-file)

quiet_cmd_flex  = FLEX     $@
quiet_cmd_bison = BISON    $@

# Create directory unless it exists
quiet_cmd_mkdir = MKDIR    $(dir $@)
      cmd_mkdir = mkdir -p $(dir $@)
     rule_mkdir = $(if $(wildcard $(dir $@)),,@$(call echo-cmd,mkdir) $(cmd_mkdir))

# Compile command
quiet_cmd_cc_o_c = CC       $@
      cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<

quiet_cmd_host_cc_o_c = HOSTCC   $@
      cmd_host_cc_o_c = $(HOSTCC) $(host_c_flags) -c -o $@ $<

quiet_cmd_cxx_o_c = CXX      $@
      cmd_cxx_o_c = $(CXX) $(cxx_flags) -c -o $@ $<

quiet_cmd_cpp_i_c = CPP      $@
      cmd_cpp_i_c = $(CC) $(c_flags) -E -o $@ $<

quiet_cmd_cc_s_c = AS       $@
      cmd_cc_s_c = $(CC) $(c_flags) -S -o $@ $<

quiet_cmd_gen = GEN      $@

# Link agregate command
# If there's nothing to link, create empty $@ object.
quiet_cmd_ld_multi = LD       $@
      cmd_ld_multi = $(if $(strip $(obj-y)),\
                     $(LD) -r -o $@  $(filter $(obj-y),$^),rm -f $@; $(AR) rcs $@)

quiet_cmd_host_ld_multi = HOSTLD   $@
      cmd_host_ld_multi = $(if $(strip $(obj-y)),\
                          $(HOSTLD) -r -o $@  $(filter $(obj-y),$^),rm -f $@; $(HOSTAR) rcs $@)

ifneq ($(filter $(obj),$(hostprogs)),)
  host = host_
endif

# Build rules
$(OUTPUT)%.o: %.c FORCE
	$(call rule_mkdir)
	$(call if_changed_dep,$(host)cc_o_c)

$(OUTPUT)%.o: %.cpp FORCE
	$(call rule_mkdir)
	$(call if_changed_dep,cxx_o_c)

$(OUTPUT)%.o: %.S FORCE
	$(call rule_mkdir)
	$(call if_changed_dep,$(host)cc_o_c)

$(OUTPUT)%.i: %.c FORCE
	$(call rule_mkdir)
	$(call if_changed_dep,cpp_i_c)

$(OUTPUT)%.s: %.S FORCE
	$(call rule_mkdir)
	$(call if_changed_dep,cpp_i_c)

$(OUTPUT)%.s: %.c FORCE
	$(call rule_mkdir)
	$(call if_changed_dep,cc_s_c)

# Gather build data:
#   obj-y        - list of build objects
#   subdir-y     - list of directories to nest
#   subdir-obj-y - list of directories objects 'dir/$(obj)-in.o'
obj-y        := $($(obj)-y)
subdir-y     := $(patsubst %/,%,$(filter %/, $(obj-y)))
obj-y        := $(patsubst %/, %/$(obj)-in.o, $(obj-y))
subdir-obj-y := $(filter %/$(obj)-in.o, $(obj-y))

# '$(OUTPUT)/dir' prefix to all objects
objprefix    := $(subst ./,,$(OUTPUT)$(dir)/)
obj-y        := $(addprefix $(objprefix),$(obj-y))
subdir-obj-y := $(addprefix $(objprefix),$(subdir-obj-y))

# Final '$(obj)-in.o' object
in-target := $(objprefix)$(obj)-in.o

PHONY += $(subdir-y)

$(subdir-y):
	$(Q)$(MAKE) -f $(build-dir)/Makefile.build dir=$(dir)/$@ obj=$(obj)

$(sort $(subdir-obj-y)): $(subdir-y) ;

$(in-target): $(obj-y) FORCE
	$(call rule_mkdir)
	$(call if_changed,$(host)ld_multi)

__build: $(in-target)
	@:

PHONY += FORCE
FORCE:

# Include all cmd files to get all the dependency rules
# for all objects included
targets   := $(wildcard $(sort $(obj-y) $(in-target) $(MAKECMDGOALS)))
cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))

ifneq ($(cmd_files),)
  include $(cmd_files)
endif

.PHONY: $(PHONY)
><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>committer</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/sound/soc/zte/zx-spdif.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/sound/soc/zte/zx-spdif.c?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>98fe974ee4e20121253de7f61fc8d01bdb3821c1</a> /<a href='/cgit.cgi/linux/net-next.git/tree/sound/soc/zte/zx-spdif.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>sound/soc/zte/zx-spdif.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/sound/soc/zte/zx-spdif.c?h=nds-private-remove&amp;id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/sound/soc/zte/zx-spdif.c?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e&amp;id2=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>diff</a>)</td></tr></table>
<div class='commit-subject'>drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()</div><div class='commit-msg'>I've seen this trigger twice now, where the i915_gem_object_to_ggtt()
call in intel_unpin_fb_obj() returns NULL, resulting in an oops
immediately afterwards as the (inlined) call to i915_vma_unpin_fence()
tries to dereference it.

It seems to be some race condition where the object is going away at
shutdown time, since both times happened when shutting down the X
server.  The call chains were different:

 - VT ioctl(KDSETMODE, KD_TEXT):

    intel_cleanup_plane_fb+0x5b/0xa0 [i915]
    drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper]
    intel_atomic_commit_tail+0x749/0xfe0 [i915]
    intel_atomic_commit+0x3cb/0x4f0 [i915]
    drm_atomic_commit+0x4b/0x50 [drm]
    restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper]
    drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper]
    drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper]
    intel_fbdev_set_par+0x18/0x70 [i915]
    fb_set_var+0x236/0x460
    fbcon_blank+0x30f/0x350
    do_unblank_screen+0xd2/0x1a0
    vt_ioctl+0x507/0x12a0
    tty_ioctl+0x355/0xc30
    do_vfs_ioctl+0xa3/0x5e0
    SyS_ioctl+0x79/0x90
    entry_SYSCALL_64_fastpath+0x13/0x94

 - i915 unpin_work workqueue:

    intel_unpin_work_fn+0x58/0x140 [i915]
    process_one_work+0x1f1/0x480
    worker_thread+0x48/0x4d0
    kthread+0x101/0x140

and this patch purely papers over the issue by adding a NULL pointer
check and a WARN_ON_ONCE() to avoid the oops that would then generally
make the machine unresponsive.

Other callers of i915_gem_object_to_ggtt() seem to also check for the
returned pointer being NULL and warn about it, so this clearly has
happened before in other places.

[ Reported it originally to the i915 developers on Jan 8, applying the
  ugly workaround on my own now after triggering the problem for the
  second time with no feedback.

  This is likely to be the same bug reported as

     https://bugs.freedesktop.org/show_bug.cgi?id=98829
     https://bugs.freedesktop.org/show_bug.cgi?id=99134

  which has a patch for the underlying problem, but it hasn't gotten to
  me, so I'm applying the workaround. ]

Cc: Daniel Vetter &lt;daniel.vetter@intel.com&gt;
Cc: Jani Nikula &lt;jani.nikula@linux.intel.com&gt;
Cc: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Cc: Chris Wilson &lt;chris@chris-wilson.co.uk&gt;
Cc: Maarten Lankhorst &lt;maarten.lankhorst@linux.intel.com&gt;
Cc: Tvrtko Ursulin &lt;tvrtko.ursulin@intel.com&gt;
Cc: Imre Deak &lt;imre.deak@intel.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>Diffstat</a> (limited to 'sound/soc/zte/zx-spdif.c')</div><table summary='diffstat' class='diffstat'>