Merge branch 'linus' into perf/core, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>

17 files changed, 136 insertions, 145 deletions

diff --git a/tools/arch/x86/include/asm/cpufeatures.h b/tools/arch/x86/include/asm/cpufeatures.h
index 1188bc849ee3..a39629206864 100644
--- a/tools/arch/x86/include/asm/cpufeatures.h
+++ b/tools/arch/x86/include/asm/cpufeatures.h
@@ -194,6 +194,8 @@
 #define X86_FEATURE_PROC_FEEDBACK ( 7*32+ 9) /* AMD ProcFeedbackInterface */
 
 #define X86_FEATURE_INTEL_PT	( 7*32+15) /* Intel Processor Trace */
+#define X86_FEATURE_AVX512_4VNNIW (7*32+16) /* AVX-512 Neural Network Instructions */
+#define X86_FEATURE_AVX512_4FMAPS (7*32+17) /* AVX-512 Multiply Accumulation Single precision */
 
 /* Virtualization flags: Linux defined, word 8 */
 #define X86_FEATURE_TPR_SHADOW  ( 8*32+ 0) /* Intel TPR Shadow */
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 4490601a9235..e8a1f699058a 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -754,7 +754,7 @@ static struct rela *find_switch_table(struct objtool_file *file,
 		if (insn->type == INSN_JUMP_UNCONDITIONAL &&
 		    insn->jump_dest &&
 		    (insn->jump_dest->offset <= insn->offset ||
-		     insn->jump_dest->offset >= orig_insn->offset))
+		     insn->jump_dest->offset > orig_insn->offset))
 		    break;
 
 		text_rela = find_rela_by_dest_range(insn->sec, insn->offset,
diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 66676cb8effe..641b40234a9d 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -1353,8 +1353,8 @@ static int hist_browser__show_hierarchy_entry(struct hist_browser *browser,
 		}
 
 		if (first) {
-			ui_browser__printf(&browser->b, "%c", folded_sign);
-			width--;
+			ui_browser__printf(&browser->b, "%c ", folded_sign);
+			width -= 2;
 			first = false;
 		} else {
 			ui_browser__printf(&browser->b, "  ");
@@ -1377,8 +1377,10 @@ static int hist_browser__show_hierarchy_entry(struct hist_browser *browser,
 		width -= hpp.buf - s;
 	}
 
-	ui_browser__write_nstring(&browser->b, "", hierarchy_indent);
-	width -= hierarchy_indent;
+	if (!first) {
+		ui_browser__write_nstring(&browser->b, "", hierarchy_indent);
+		width -= hierarchy_indent;
+	}
 
 	if (column >= browser->b.horiz_scroll) {
 		char s[2048];
@@ -1397,7 +1399,13 @@ static int hist_browser__show_hierarchy_entry(struct hist_browser *browser,
 		}
 
 		perf_hpp_list__for_each_format(entry->hpp_list, fmt) {
-			ui_browser__write_nstring(&browser->b, "", 2);
+			if (first) {
+				ui_browser__printf(&browser->b, "%c ", folded_sign);
+				first = false;
+			} else {
+				ui_browser__write_nstring(&browser->b, "", 2);
+			}
+
 			width -= 2;
 
 			/*
@@ -1571,10 +1579,11 @@ static int hists_browser__scnprintf_hierarchy_headers(struct hist_browser *brows
 	int indent = hists->nr_hpp_node - 2;
 	bool first_node, first_col;
 
-	ret = scnprintf(buf, size, " ");
+	ret = scnprintf(buf, size, "  ");
 	if (advance_hpp_check(&dummy_hpp, ret))
 		return ret;
 
+	first_node = true;
 	/* the first hpp_list_node is for overhead columns */
 	fmt_node = list_first_entry(&hists->hpp_formats,
 				    struct perf_hpp_list_node, list);
@@ -1589,12 +1598,16 @@ static int hists_browser__scnprintf_hierarchy_headers(struct hist_browser *brows
 		ret = scnprintf(dummy_hpp.buf, dummy_hpp.size, "  ");
 		if (advance_hpp_check(&dummy_hpp, ret))
 			break;
+
+		first_node = false;
 	}
 
-	ret = scnprintf(dummy_hpp.buf, dummy_hpp.size, "%*s",
-			indent * HIERARCHY_INDENT, "");
-	if (advance_hpp_check(&dummy_hpp, ret))
-		return ret;
+	if (!first_node) {
+		ret = scnprintf(dummy_hpp.buf, dummy_hpp.size, "%*s",
+				indent * HIERARCHY_INDENT, "");
+		if (advance_hpp_check(&dummy_hpp, ret))
+			return ret;
+	}
 
 	first_node = true;
 	list_for_each_entry_continue(fmt_node, &hists->hpp_formats, list) {
diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index e1be4132054d..6770a9645609 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -1601,18 +1601,18 @@ static void hists__hierarchy_output_resort(struct hists *hists,
 		if (prog)
 			ui_progress__update(prog, 1);
 
+		hists->nr_entries++;
+		if (!he->filtered) {
+			hists->nr_non_filtered_entries++;
+			hists__calc_col_len(hists, he);
+		}
+
 		if (!he->leaf) {
 			hists__hierarchy_output_resort(hists, prog,
 						       &he->hroot_in,
 						       &he->hroot_out,
 						       min_callchain_hits,
 						       use_callchain);
-			hists->nr_entries++;
-			if (!he->filtered) {
-				hists->nr_non_filtered_entries++;
-				hists__calc_col_len(hists, he);
-			}
-
 			continue;
 		}
 
diff --git a/tools/power/acpi/Makefile.config b/tools/power/acpi/Makefile.config
index a538ff44b108..a1883bbb0144 100644
--- a/tools/power/acpi/Makefile.config
+++ b/tools/power/acpi/Makefile.config
@@ -8,18 +8,19 @@
 # as published by the Free Software Foundation; version 2
 # of the License.
 
-include ../../../../scripts/Makefile.include
-
-OUTPUT=./
-ifeq ("$(origin O)", "command line")
-	OUTPUT := $(O)/
+ifeq ($(srctree),)
+srctree := $(patsubst %/,%,$(dir $(shell pwd)))
+srctree := $(patsubst %/,%,$(dir $(srctree)))
+#$(info Determined 'srctree' to be $(srctree))
 endif
 
-ifneq ($(OUTPUT),)
-# check that the output directory actually exists
-OUTDIR := $(shell cd $(OUTPUT) && /bin/pwd)
-$(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
+include $(srctree)/../../scripts/Makefile.include
+
+OUTPUT=$(srctree)/
+ifeq ("$(origin O)", "command line")
+	OUTPUT := $(O)/power/acpi/
 endif
+#$(info Determined 'OUTPUT' to be $(OUTPUT))
 
 # --- CONFIGURATION BEGIN ---
 
@@ -70,8 +71,8 @@ WARNINGS := -Wall
 WARNINGS += $(call cc-supports,-Wstrict-prototypes)
 WARNINGS += $(call cc-supports,-Wdeclaration-after-statement)
 
-KERNEL_INCLUDE := ../../../include
-ACPICA_INCLUDE := ../../../drivers/acpi/acpica
+KERNEL_INCLUDE := $(OUTPUT)include
+ACPICA_INCLUDE := $(srctree)/../../../drivers/acpi/acpica
 CFLAGS += -D_LINUX -I$(KERNEL_INCLUDE) -I$(ACPICA_INCLUDE)
 CFLAGS += $(WARNINGS)
 
diff --git a/tools/power/acpi/Makefile.rules b/tools/power/acpi/Makefile.rules
index ec87a9e562c0..373738338f51 100644
--- a/tools/power/acpi/Makefile.rules
+++ b/tools/power/acpi/Makefile.rules
@@ -8,28 +8,42 @@
 # as published by the Free Software Foundation; version 2
 # of the License.
 
-$(OUTPUT)$(TOOL): $(TOOL_OBJS) FORCE
-	$(ECHO) "  LD      " $@
-	$(QUIET) $(LD) $(CFLAGS) $(LDFLAGS) $(TOOL_OBJS) -L$(OUTPUT) -o $@
+objdir := $(OUTPUT)tools/$(TOOL)/
+toolobjs := $(addprefix $(objdir),$(TOOL_OBJS))
+$(OUTPUT)$(TOOL): $(toolobjs) FORCE
+	$(ECHO) "  LD      " $(subst $(OUTPUT),,$@)
+	$(QUIET) $(LD) $(CFLAGS) $(LDFLAGS) $(toolobjs) -L$(OUTPUT) -o $@
+	$(ECHO) "  STRIP   " $(subst $(OUTPUT),,$@)
 	$(QUIET) $(STRIPCMD) $@
 
-$(OUTPUT)%.o: %.c
-	$(ECHO) "  CC      " $@
+$(KERNEL_INCLUDE):
+	$(ECHO) "  MKDIR   " $(subst $(OUTPUT),,$@)
+	$(QUIET) mkdir -p $(KERNEL_INCLUDE)
+	$(ECHO) "  CP      " $(subst $(OUTPUT),,$@)
+	$(QUIET) cp -rf $(srctree)/../../../include/acpi $(KERNEL_INCLUDE)/
+
+$(objdir)%.o: %.c $(KERNEL_INCLUDE)
+	$(ECHO) "  CC      " $(subst $(OUTPUT),,$@)
 	$(QUIET) $(CC) -c $(CFLAGS) -o $@ $<
 
 all: $(OUTPUT)$(TOOL)
 clean:
-	-find $(OUTPUT) \( -not -type d \) \
-	-and \( -name '*~' -o -name '*.[oas]' \) \
-	-type f -print \
-	 | xargs rm -f
-	-rm -f $(OUTPUT)$(TOOL)
+	$(ECHO) "  RMOBJ   " $(subst $(OUTPUT),,$(objdir))
+	$(QUIET) find $(objdir) \( -not -type d \)\
+		 -and \( -name '*~' -o -name '*.[oas]' \)\
+		 -type f -print | xargs rm -f
+	$(ECHO) "  RM      " $(TOOL)
+	$(QUIET) rm -f $(OUTPUT)$(TOOL)
+	$(ECHO) "  RMINC   " $(subst $(OUTPUT),,$(KERNEL_INCLUDE))
+	$(QUIET) rm -rf $(KERNEL_INCLUDE)
 
 install-tools:
-	$(INSTALL) -d $(DESTDIR)${sbindir}
-	$(INSTALL_PROGRAM) $(OUTPUT)$(TOOL) $(DESTDIR)${sbindir}
+	$(ECHO) "  INST    " $(TOOL)
+	$(QUIET) $(INSTALL) -d $(DESTDIR)$(sbindir)
+	$(QUIET) $(INSTALL_PROGRAM) $(OUTPUT)$(TOOL) $(DESTDIR)$(sbindir)
 uninstall-tools:
-	- rm -f $(DESTDIR)${sbindir}/$(TOOL)
+	$(ECHO) "  UNINST  " $(TOOL)
+	$(QUIET) rm -f $(DESTDIR)$(sbindir)/$(TOOL)
 
 install: all install-tools $(EXTRA_INSTALL)
 uninstall: uninstall-tools $(EXTRA_UNINSTALL)
diff --git a/tools/power/acpi/tools/acpidbg/Makefile b/tools/power/acpi/tools/acpidbg/Makefile
index 352df4b41ae9..f2d06e773eb4 100644
--- a/tools/power/acpi/tools/acpidbg/Makefile
+++ b/tools/power/acpi/tools/acpidbg/Makefile
@@ -17,9 +17,7 @@ vpath %.c \
 	../../os_specific/service_layers\
 	.
 CFLAGS += -DACPI_APPLICATION -DACPI_SINGLE_THREAD -DACPI_DEBUGGER\
-	-I.\
-	-I../../../../../drivers/acpi/acpica\
-	-I../../../../../include
+	-I.
 LDFLAGS += -lpthread
 TOOL_OBJS = \
 	acpidbg.o
diff --git a/tools/power/acpi/tools/acpidbg/acpidbg.c b/tools/power/acpi/tools/acpidbg/acpidbg.c
index a88ac45b7756..4308362d7068 100644
--- a/tools/power/acpi/tools/acpidbg/acpidbg.c
+++ b/tools/power/acpi/tools/acpidbg/acpidbg.c
@@ -12,10 +12,16 @@
 #include <acpi/acpi.h>
 
 /* Headers not included by include/acpi/platform/aclinux.h */
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <error.h>
 #include <stdbool.h>
 #include <fcntl.h>
 #include <assert.h>
-#include <linux/circ_buf.h>
+#include <sys/select.h>
+#include "../../../../../include/linux/circ_buf.h"
 
 #define ACPI_AML_FILE		"/sys/kernel/debug/acpi/acpidbg"
 #define ACPI_AML_SEC_TICK	1
diff --git a/tools/power/acpi/tools/acpidump/Makefile b/tools/power/acpi/tools/acpidump/Makefile
index 04b5db7c7c0b..f7c7af1f9258 100644
--- a/tools/power/acpi/tools/acpidump/Makefile
+++ b/tools/power/acpi/tools/acpidump/Makefile
@@ -19,9 +19,7 @@ vpath %.c \
 	./\
 	../../common\
 	../../os_specific/service_layers
-CFLAGS += -DACPI_DUMP_APP -I.\
-	-I../../../../../drivers/acpi/acpica\
-	-I../../../../../include
+CFLAGS += -DACPI_DUMP_APP -I.
 TOOL_OBJS = \
 	apdump.o\
 	apfiles.o\
@@ -49,7 +47,9 @@ TOOL_OBJS = \
 
 include ../../Makefile.rules
 
-install-man: ../../man/acpidump.8
-	$(INSTALL_DATA) -D $< $(DESTDIR)${mandir}/man8/acpidump.8
+install-man: $(srctree)/man/acpidump.8
+	$(ECHO) "  INST    " acpidump.8
+	$(QUIET) $(INSTALL_DATA) -D $< $(DESTDIR)$(mandir)/man8/acpidump.8
 uninstall-man:
-	- rm -f $(DESTDIR)${mandir}/man8/acpidump.8
+	$(ECHO) "  UNINST  " acpidump.8
+	$(QUIET) rm -f $(DESTDIR)$(mandir)/man8/acpidump.8
diff --git a/tools/power/cpupower/utils/cpufreq-set.c b/tools/power/cpupower/utils/cpufreq-set.c
index b4bf76971dc9..1eef0aed6423 100644
--- a/tools/power/cpupower/utils/cpufreq-set.c
+++ b/tools/power/cpupower/utils/cpufreq-set.c
@@ -296,7 +296,7 @@ int cmd_freq_set(int argc, char **argv)
 			struct cpufreq_affected_cpus *cpus;
 
 			if (!bitmask_isbitset(cpus_chosen, cpu) ||
-			    cpupower_is_cpu_online(cpu))
+			    cpupower_is_cpu_online(cpu) != 1)
 				continue;
 
 			cpus = cpufreq_get_related_cpus(cpu);
@@ -316,10 +316,7 @@ int cmd_freq_set(int argc, char **argv)
 	     cpu <= bitmask_last(cpus_chosen); cpu++) {
 
 		if (!bitmask_isbitset(cpus_chosen, cpu) ||
-		    cpupower_is_cpu_online(cpu))
-			continue;
-
-		if (cpupower_is_cpu_online(cpu) != 1)
+		    cpupower_is_cpu_online(cpu) != 1)
 			continue;
 
 		printf(_("Setting cpu: %d\n"), cpu);
diff --git a/tools/virtio/ringtest/Makefile b/tools/virtio/ringtest/Makefile
index 877a8a4721b6..c012edbdb13b 100644
--- a/tools/virtio/ringtest/Makefile
+++ b/tools/virtio/ringtest/Makefile
@@ -3,8 +3,8 @@ all:
 all: ring virtio_ring_0_9 virtio_ring_poll virtio_ring_inorder ptr_ring noring
 
 CFLAGS += -Wall
-CFLAGS += -pthread -O2 -ggdb
-LDFLAGS += -pthread -O2 -ggdb
+CFLAGS += -pthread -O2 -ggdb -flto -fwhole-program
+LDFLAGS += -pthread -O2 -ggdb -flto -fwhole-program
 
 main.o: main.c main.h
 ring.o: ring.c main.h
diff --git a/tools/virtio/ringtest/main.c b/tools/virtio/ringtest/main.c
index 147abb452a6c..f31353fac541 100644
--- a/tools/virtio/ringtest/main.c
+++ b/tools/virtio/ringtest/main.c
@@ -96,7 +96,13 @@ void set_affinity(const char *arg)
 	assert(!ret);
 }
 
-static void run_guest(void)
+void poll_used(void)
+{
+	while (used_empty())
+		busy_wait();
+}
+
+static void __attribute__((__flatten__)) run_guest(void)
 {
 	int completed_before;
 	int completed = 0;
@@ -141,7 +147,7 @@ static void run_guest(void)
 		assert(completed <= bufs);
 		assert(started <= bufs);
 		if (do_sleep) {
-			if (enable_call())
+			if (used_empty() && enable_call())
 				wait_for_call();
 		} else {
 			poll_used();
@@ -149,7 +155,13 @@ static void run_guest(void)
 	}
 }
 
-static void run_host(void)
+void poll_avail(void)
+{
+	while (avail_empty())
+		busy_wait();
+}
+
+static void __attribute__((__flatten__)) run_host(void)
 {
 	int completed_before;
 	int completed = 0;
@@ -160,7 +172,7 @@ static void run_host(void)
 
 	for (;;) {
 		if (do_sleep) {
-			if (enable_kick())
+			if (avail_empty() && enable_kick())
 				wait_for_kick();
 		} else {
 			poll_avail();
diff --git a/tools/virtio/ringtest/main.h b/tools/virtio/ringtest/main.h
index 16917acb0ade..34e63cc4c572 100644
--- a/tools/virtio/ringtest/main.h
+++ b/tools/virtio/ringtest/main.h
@@ -56,15 +56,15 @@ void alloc_ring(void);
 int add_inbuf(unsigned, void *, void *);
 void *get_buf(unsigned *, void **);
 void disable_call();
+bool used_empty();
 bool enable_call();
 void kick_available();
-void poll_used();
 /* host side */
 void disable_kick();
+bool avail_empty();
 bool enable_kick();
 bool use_buf(unsigned *, void **);
 void call_used();
-void poll_avail();
 
 /* implemented by main */
 extern bool do_sleep;
diff --git a/tools/virtio/ringtest/noring.c b/tools/virtio/ringtest/noring.c
index eda2f4824130..b8d1c1daac7c 100644
--- a/tools/virtio/ringtest/noring.c
+++ b/tools/virtio/ringtest/noring.c
@@ -24,8 +24,9 @@ void *get_buf(unsigned *lenp, void **bufp)
 	return "Buffer";
 }
 
-void poll_used(void)
+bool used_empty()
 {
+	return false;
 }
 
 void disable_call()
@@ -54,8 +55,9 @@ bool enable_kick()
 	assert(0);
 }
 
-void poll_avail(void)
+bool avail_empty()
 {
+	return false;
 }
 
 bool use_buf(unsigned *lenp, void **bufp)
diff --git a/tools/virtio/ringtest/ptr_ring.c b/tools/virtio/ringtest/ptr_ring.c
index bd2ad1d3b7a9..635b07b4fdd3 100644
--- a/tools/virtio/ringtest/ptr_ring.c
+++ b/tools/virtio/ringtest/ptr_ring.c
@@ -133,18 +133,9 @@ void *get_buf(unsigned *lenp, void **bufp)
 	return datap;
 }
 
-void poll_used(void)
+bool used_empty()
 {
-	void *b;
-
-	do {
-		if (tailcnt == headcnt || __ptr_ring_full(&array)) {
-			b = NULL;
-			barrier();
-		} else {
-			b = "Buffer\n";
-		}
-	} while (!b);
+	return (tailcnt == headcnt || __ptr_ring_full(&array));
 }
 
 void disable_call()
@@ -173,14 +164,9 @@ bool enable_kick()
 	assert(0);
 }
 
-void poll_avail(void)
+bool avail_empty()
 {
-	void *b;
-
-	do {
-		barrier();
-		b = __ptr_ring_peek(&array);
-	} while (!b);
+	return !__ptr_ring_peek(&array);
 }
 
 bool use_buf(unsigned *lenp, void **bufp)
diff --git a/tools/virtio/ringtest/ring.c b/tools/virtio/ringtest/ring.c
index c25c8d248b6b..747c5dd47be8 100644
--- a/tools/virtio/ringtest/ring.c
+++ b/tools/virtio/ringtest/ring.c
@@ -163,12 +163,11 @@ void *get_buf(unsigned *lenp, void **bufp)
 	return datap;
 }
 
-void poll_used(void)
+bool used_empty()
 {
 	unsigned head = (ring_size - 1) & guest.last_used_idx;
 
-	while (ring[head].flags & DESC_HW)
-		busy_wait();
+	return (ring[head].flags & DESC_HW);
 }
 
 void disable_call()
@@ -180,13 +179,11 @@ void disable_call()
 
 bool enable_call()
 {
-	unsigned head = (ring_size - 1) & guest.last_used_idx;
-
 	event->call_index = guest.last_used_idx;
 	/* Flush call index write */
 	/* Barrier D (for pairing) */
 	smp_mb();
-	return ring[head].flags & DESC_HW;
+	return used_empty();
 }
 
 void kick_available(void)
@@ -213,20 +210,17 @@ void disable_kick()
 
 bool enable_kick()
 {
-	unsigned head = (ring_size - 1) & host.used_idx;
-
 	event->kick_index = host.used_idx;
 	/* Barrier C (for pairing) */
 	smp_mb();
-	return !(ring[head].flags & DESC_HW);
+	return avail_empty();
 }
 
-void poll_avail(void)
+bool avail_empty()
 {
 	unsigned head = (ring_size - 1) & host.used_idx;
 
-	while (!(ring[head].flags & DESC_HW))
-		busy_wait();
+	return !(ring[head].flags & DESC_HW);
 }
 
 bool use_buf(unsigned *lenp, void **bufp)
diff --git a/tools/virtio/ringtest/virtio_ring_0_9.c b/tools/virtio/ringtest/virtio_ring_0_9.c
index 761866212aac..bbc3043b2fb1 100644
--- a/tools/virtio/ringtest/virtio_ring_0_9.c
+++ b/tools/virtio/ringtest/virtio_ring_0_9.c
@@ -194,24 +194,16 @@ void *get_buf(unsigned *lenp, void **bufp)
 	return datap;
 }
 
-void poll_used(void)
+bool used_empty()
 {
+	unsigned short last_used_idx = guest.last_used_idx;
 #ifdef RING_POLL
-	unsigned head = (ring_size - 1) & guest.last_used_idx;
+	unsigned short head = last_used_idx & (ring_size - 1);
+	unsigned index = ring.used->ring[head].id;
 
-	for (;;) {
-		unsigned index = ring.used->ring[head].id;
-
-		if ((index ^ guest.last_used_idx ^ 0x8000) & ~(ring_size - 1))
-			busy_wait();
-		else
-			break;
-	}
+	return (index ^ last_used_idx ^ 0x8000) & ~(ring_size - 1);
 #else
-	unsigned head = guest.last_used_idx;
-
-	while (ring.used->idx == head)
-		busy_wait();
+	return ring.used->idx == last_used_idx;
 #endif
 }
 
@@ -224,22 +216,11 @@ void disable_call()
 
 bool enable_call()
 {
-	unsigned short last_used_idx;
-
-	vring_used_event(&ring) = (last_used_idx = guest.last_used_idx);
+	vring_used_event(&ring) = guest.last_used_idx;
 	/* Flush call index write */
 	/* Barrier D (for pairing) */
 	smp_mb();
-#ifdef RING_POLL
-	{
-		unsigned short head = last_used_idx & (ring_size - 1);
-		unsigned index = ring.used->ring[head].id;
-
-		return (index ^ last_used_idx ^ 0x8000) & ~(ring_size - 1);
-	}
-#else
-	return ring.used->idx == last_used_idx;
-#endif
+	return used_empty();
 }
 
 void kick_available(void)
@@ -266,36 +247,21 @@ void disable_kick()
 
 bool enable_kick()
 {
-	unsigned head = host.used_idx;
-
-	vring_avail_event(&ring) = head;
+	vring_avail_event(&ring) = host.used_idx;
 	/* Barrier C (for pairing) */
 	smp_mb();
-#ifdef RING_POLL
-	{
-		unsigned index = ring.avail->ring[head & (ring_size - 1)];
-
-		return (index ^ head ^ 0x8000) & ~(ring_size - 1);
-	}
-#else
-	return head == ring.avail->idx;
-#endif
+	return avail_empty();
 }
 
-void poll_avail(void)
+bool avail_empty()
 {
 	unsigned head = host.used_idx;
 #ifdef RING_POLL
-	for (;;) {
-		unsigned index = ring.avail->ring[head & (ring_size - 1)];
-		if ((index ^ head ^ 0x8000) & ~(ring_size - 1))
-			busy_wait();
-		else
-			break;
-	}
+	unsigned index = ring.avail->ring[head & (ring_size - 1)];
+
+	return ((index ^ head ^ 0x8000) & ~(ring_size - 1));
 #else
-	while (ring.avail->idx == head)
-		busy_wait();
+	return head == ring.avail->idx;
 #endif
 }