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cpu: convert queued work to a QSIMPLEQ

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We convert queued work to a QSIMPLEQ, instead of
open-coding it.

While at it, make sure that all accesses to the list are
performed while holding the list's lock.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Robert Foley <robert.foley@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200609200738.445-3-robert.foley@linaro.org>
Message-Id: <20200612190237.30436-6-alex.bennee@linaro.org>
This commit is contained in:
Emilio G. Cota 2020-06-12 20:02:24 +01:00 committed by Alex Bennée
parent 0aebab04b9
commit 0c0fcc2052
4 changed files with 24 additions and 22 deletions
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25
cpus-common.c
View File

@ -97,7 +97,7 @@ void cpu_list_remove(CPUState *cpu)
}
struct qemu_work_item {
struct qemu_work_item *next;
QSIMPLEQ_ENTRY(qemu_work_item) node;
run_on_cpu_func func;
run_on_cpu_data data;
bool free, exclusive, done;
@ -106,13 +106,7 @@ struct qemu_work_item {
static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi)
{
qemu_mutex_lock(&cpu->work_mutex);
if (cpu->queued_work_first == NULL) {
cpu->queued_work_first = wi;
} else {
cpu->queued_work_last->next = wi;
}
cpu->queued_work_last = wi;
wi->next = NULL;
QSIMPLEQ_INSERT_TAIL(&cpu->work_list, wi, node);
wi->done = false;
qemu_mutex_unlock(&cpu->work_mutex);
@ -306,17 +300,14 @@ void process_queued_cpu_work(CPUState *cpu)
{
struct qemu_work_item *wi;
if (cpu->queued_work_first == NULL) {
qemu_mutex_lock(&cpu->work_mutex);
if (QSIMPLEQ_EMPTY(&cpu->work_list)) {
qemu_mutex_unlock(&cpu->work_mutex);
return;
}
qemu_mutex_lock(&cpu->work_mutex);
while (cpu->queued_work_first != NULL) {
wi = cpu->queued_work_first;
cpu->queued_work_first = wi->next;
if (!cpu->queued_work_first) {
cpu->queued_work_last = NULL;
}
while (!QSIMPLEQ_EMPTY(&cpu->work_list)) {
wi = QSIMPLEQ_FIRST(&cpu->work_list);
QSIMPLEQ_REMOVE_HEAD(&cpu->work_list, node);
qemu_mutex_unlock(&cpu->work_mutex);
if (wi->exclusive) {
/* Running work items outside the BQL avoids the following deadlock:

14
cpus.c
View File

@ -97,9 +97,19 @@ bool cpu_is_stopped(CPUState *cpu)
return cpu->stopped || !runstate_is_running();
}
static inline bool cpu_work_list_empty(CPUState *cpu)
{
bool ret;
qemu_mutex_lock(&cpu->work_mutex);
ret = QSIMPLEQ_EMPTY(&cpu->work_list);
qemu_mutex_unlock(&cpu->work_mutex);
return ret;
}
static bool cpu_thread_is_idle(CPUState *cpu)
{
if (cpu->stop || cpu->queued_work_first) {
if (cpu->stop || !cpu_work_list_empty(cpu)) {
return false;
}
if (cpu_is_stopped(cpu)) {
@ -1518,7 +1528,7 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg)
cpu = first_cpu;
}
while (cpu && !cpu->queued_work_first && !cpu->exit_request) {
while (cpu && cpu_work_list_empty(cpu) && !cpu->exit_request) {
atomic_mb_set(&tcg_current_rr_cpu, cpu);
current_cpu = cpu;

1
hw/core/cpu.c
View File

@ -370,6 +370,7 @@ static void cpu_common_initfn(Object *obj)
cpu->nr_threads = 1;
qemu_mutex_init(&cpu->work_mutex);
QSIMPLEQ_INIT(&cpu->work_list);
QTAILQ_INIT(&cpu->breakpoints);
QTAILQ_INIT(&cpu->watchpoints);

6
include/hw/core/cpu.h
View File

@ -331,8 +331,8 @@ struct qemu_work_item;
* @opaque: User data.
* @mem_io_pc: Host Program Counter at which the memory was accessed.
* @kvm_fd: vCPU file descriptor for KVM.
* @work_mutex: Lock to prevent multiple access to queued_work_*.
* @queued_work_first: First asynchronous work pending.
* @work_mutex: Lock to prevent multiple access to @work_list.
* @work_list: List of pending asynchronous work.
* @trace_dstate_delayed: Delayed changes to trace_dstate (includes all changes
* to @trace_dstate).
* @trace_dstate: Dynamic tracing state of events for this vCPU (bitmask).
@ -376,7 +376,7 @@ struct CPUState {
sigjmp_buf jmp_env;
QemuMutex work_mutex;
struct qemu_work_item *queued_work_first, *queued_work_last;
QSIMPLEQ_HEAD(, qemu_work_item) work_list;
CPUAddressSpace *cpu_ases;
int num_ases;