+ arch-x86-kernel-acpi-cstatec-avoid-using-work_on_cpu.patch added to -mm tree

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The patch titled
     arch/x86/kernel/acpi/cstate.c: avoid using work_on_cpu()
has been added to the -mm tree.  Its filename is
     arch-x86-kernel-acpi-cstatec-avoid-using-work_on_cpu.patch

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*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this

The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/

------------------------------------------------------
Subject: arch/x86/kernel/acpi/cstate.c: avoid using work_on_cpu()
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>

A series of patches which

- removes all but one callers of work_on_cpu() by switching then to
  smp_call_function_single()

- converts work_on_cpu() to create a kernel thread on depend, thus
  avoidin the various deadlock scenarios which we keep on experiencing and
  thinking up.

All cheerfully untested.


This patch:

Atttempting to rid us of the problematic work_on_cpu().  Just use
smp_call_fuction_single() here.

Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Zhao Yakui <yakui.zhao@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 arch/x86/kernel/acpi/cstate.c |   36 +++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff -puN arch/x86/kernel/acpi/cstate.c~arch-x86-kernel-acpi-cstatec-avoid-using-work_on_cpu arch/x86/kernel/acpi/cstate.c
--- a/arch/x86/kernel/acpi/cstate.c~arch-x86-kernel-acpi-cstatec-avoid-using-work_on_cpu
+++ a/arch/x86/kernel/acpi/cstate.c
@@ -61,6 +61,12 @@ struct cstate_entry {
 };
 static struct cstate_entry *cpu_cstate_entry;	/* per CPU ptr */
 
+/* Used for the cross-CPU calls */
+struct acpi_processor_cx_cross_cpu {
+	struct acpi_processor_cx *cx;
+	long retval;
+};
+
 static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];
 
 #define MWAIT_SUBSTATE_MASK	(0xf)
@@ -75,10 +81,10 @@ static short mwait_supported[ACPI_PROCES
 
 #define NATIVE_CSTATE_BEYOND_HALT	(2)
 
-static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
+static void acpi_processor_ffh_cstate_probe_cpu(void *_cxcc)
 {
-	struct acpi_processor_cx *cx = _cx;
-	long retval;
+	struct acpi_processor_cx_cross_cpu *cxcc = _cxcc;
+	struct acpi_processor_cx *cx = cxcc->cx;
 	unsigned int eax, ebx, ecx, edx;
 	unsigned int edx_part;
 	unsigned int cstate_type; /* C-state type and not ACPI C-state type */
@@ -92,16 +98,16 @@ static long acpi_processor_ffh_cstate_pr
 	edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
 	num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;
 
-	retval = 0;
+	cxcc->retval = 0;
 	if (num_cstate_subtype < (cx->address & MWAIT_SUBSTATE_MASK)) {
-		retval = -1;
+		cxcc->retval = -1;
 		goto out;
 	}
 
 	/* mwait ecx extensions INTERRUPT_BREAK should be supported for C2/C3 */
 	if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
 	    !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) {
-		retval = -1;
+		cxcc->retval = -1;
 		goto out;
 	}
 
@@ -115,7 +121,7 @@ static long acpi_processor_ffh_cstate_pr
 			ACPI_CX_DESC_LEN, "ACPI FFH INTEL MWAIT 0x%x",
 			cx->address);
 out:
-	return retval;
+	return;
 }
 
 int acpi_processor_ffh_cstate_probe(unsigned int cpu,
@@ -123,6 +129,7 @@ int acpi_processor_ffh_cstate_probe(unsi
 {
 	struct cstate_entry *percpu_entry;
 	struct cpuinfo_x86 *c = &cpu_data(cpu);
+	struct acpi_processor_cx_cross_cpu cxcc = { .cx = cx, };
 	long retval;
 
 	if (!cpu_cstate_entry || c->cpuid_level < CPUID_MWAIT_LEAF)
@@ -135,13 +142,18 @@ int acpi_processor_ffh_cstate_probe(unsi
 	percpu_entry->states[cx->index].eax = 0;
 	percpu_entry->states[cx->index].ecx = 0;
 
-	/* Make sure we are running on right CPU */
+	/* Run acpi_processor_ffh_cstate_probe_cpu() on the target CPU */
 
-	retval = work_on_cpu(cpu, acpi_processor_ffh_cstate_probe_cpu, cx);
+	retval = smp_call_function_single(cpu,
+				acpi_processor_ffh_cstate_probe_cpu, cx, 1);
 	if (retval == 0) {
-		/* Use the hint in CST */
-		percpu_entry->states[cx->index].eax = cx->address;
-		percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;
+		retval = cxcc.retval;
+		if (retval == 0) {
+			/* Use the hint in CST */
+			percpu_entry->states[cx->index].eax = cx->address;
+			percpu_entry->states[cx->index].ecx =
+					MWAIT_ECX_INTERRUPT_BREAK;
+		}
 	}
 	return retval;
 }
_

Patches currently in -mm which might be from akpm@xxxxxxxxxxxxxxxxxxxx are

origin.patch
kernel-asyncc-fix-printk-warnings.patch
revert-rlimit-permit-setting-rlimit_nofile-to-rlim_infinity.patch
hp-wmi-fix-error-path-in-hp_wmi_bios_setup.patch
wait-prevent-exclusive-waiter-starvation-checkpatch-fixes.patch
i-need-old-gcc.patch
linux-next.patch
next-remove-localversion.patch
kvm-unbork.patch
fix-sparseirq-use-kstat_irqs_cpu-on-non-x86-architectures-too.patch
thinkpad-acpi-split-delayed-leds-stuff-clean-up-code-checkpatch-fixes.patch
x86-define-arch_want_frame_pointers-fix.patch
kernel-auditscc-fix-warning.patch
drivers-consolidate-driver_probe_done-loops-into-one-place-fix.patch
drivers-consolidate-driver_probe_done-loops-into-one-place-checkpatch-fixes.patch
sysfs-reference-sysfs_dirent-from-sysfs-inodes-fix.patch
early-platform-driver-v3-checkpatch-fixes.patch
clocksource-pass-clocksource-to-read-callback.patch
input-bcm5974-declare-alignment-usage-checkpatch-fixes.patch
mtd-rbtx4939-add-mtd-support-fix.patch
pci-quirks-unhide-overflow-device-on-i828675p-pe-chipsets.patch
raw-fix-rawctl-compat-ioctls-breakage-on-amd64-and-itanic.patch
scsi-dpt_i2o-is-bust-on-ia64.patch
drivers-ata-sata_silc-needs-dmih.patch
net-dont-use-in_atomic-in-gfp_any.patch
documentation-connector-cn_testc-dont-use-gfp_any.patch
nommu-fix-a-number-of-issues-with-the-per-mm-vma-patch.patch
page_fault-retry-with-nopage_retry.patch
page_fault-retry-with-nopage_retry-fix.patch
page_fault-retry-with-nopage_retry-fix-fix.patch
mm-add-proc-controls-for-pdflush-threads-fix.patch
mm-add-proc-controls-for-pdflush-threads-fix-fix.patch
mm-unify-some-pmd_-functions-fix-s390.patch
proc-pid-maps-dont-show-pgoff-of-pure-anon-vmas-checkpatch-fixes.patch
do_pipe-drop-its-last-user-in-arch-alpha-checkpatch-fixes.patch
epoll-keyed-wakeups-v2-teach-epoll-about-hints-coming-with-the-wakeup-key-checkpatch-fixes.patch
rtc-convert-leap_year-into-an-inline.patch
rtc-add-platform-driver-for-efi-fix.patch
drivers-video-uvesafbc-dont-use-gfp_any.patch
cpuset-fix-allocating-page-cache-slab-object-on-the-unallowed-node-when-memory-spread-is-set.patch
cpuset-fix-allocating-page-cache-slab-object-on-the-unallowed-node-when-memory-spread-is-set-fix-2.patch
pids-document-task_pgrp-task_session-is-not-safe-without-tasklist-rcu-fix.patch
nbd-add-locking-to-nbd_ioctl-checkpatch-fixes.patch
kexec-add-dmesg-log-symbols-to-proc-vmcoreinfo-lists-fix.patch
kexec-add-dmesg-log-symbols-to-proc-vmcoreinfo-lists-fix-fix.patch
arch-x86-kernel-acpi-cstatec-avoid-using-work_on_cpu.patch
arch-x86-kernel-cpu-cpufreq-acpi-cpufreqc-avoid-using-work_on_cpu.patch
arch-x86-kernel-cpu-mcheck-mce_amd_64c-avoid-using-work_on_cpu.patch
work_on_cpu-rewrite-it-to-create-a-kernel-thread-on-demand.patch
nilfs2-integrated-block-mapping-remove-nilfs-bmap-wrapper-macros-checkpatch-fixes.patch
nilfs2-inode-operations-fix.patch
nilfs2-pathname-operations-fix.patch
nilfs2-super-block-operations-fix.patch
reiser4.patch
reiser4-remove-simple_prepare_write-usage-checkpatch-fixes.patch
slab-leaks3-default-y.patch
put_bh-debug.patch
shrink_slab-handle-bad-shrinkers.patch
getblk-handle-2tb-devices.patch
getblk-handle-2tb-devices-fix.patch
undeprecate-pci_find_device.patch
notify_change-callers-must-hold-i_mutex.patch
drivers-net-bonding-bond_sysfsc-suppress-uninitialized-var-warning.patch
w1-build-fix.patch

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