Paolo Bonzini writes:
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> cpus-common.c | 25 +++++++++++++++++++++++++
> include/qom/cpu.h | 12 ++++++++++++
> 2 files changed, 37 insertions(+)
>
> diff --git a/cpus-common.c b/cpus-common.c
> index 59c8dc8..88cf5ec 100644
> --- a/cpus-common.c
> +++ b/cpus-common.c
> @@ -144,6 +144,11 @@ void async_run_on_cpu(CPUState *cpu, run_on_cpu_func
> func, void *data)
> queue_work_on_cpu(cpu, wi);
> }
>
> +typedef struct SafeWorkItem {
> + run_on_cpu_func func;
> + void *data;
> +} SafeWorkItem;
> +
> /* Wait for pending exclusive operations to complete. The exclusive lock
> must be held. */
> static inline void exclusive_idle(void)
> @@ -208,6 +213,26 @@ void cpu_exec_end(CPUState *cpu)
> qemu_mutex_unlock(&qemu_cpu_list_mutex);
> }
>
> +static void async_safe_run_on_cpu_fn(CPUState *cpu, void *data)
> +{
> + SafeWorkItem *w = data;
> +
> + start_exclusive();
> + w->func(cpu, w->data);
> + end_exclusive();
> + g_free(w);
> +}
> +
> +void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data)
> +{
> + SafeWorkItem *w = g_new(SafeWorkItem, 1);
> +
> + w->func = func;
> + w->data = data;
> +
> + async_run_on_cpu(cpu, async_safe_run_on_cpu_fn, w);
> +}
> +
> void process_queued_cpu_work(CPUState *cpu)
> {
> struct qemu_work_item *wi;
> diff --git a/include/qom/cpu.h b/include/qom/cpu.h
> index 0e04e8f..54a875e 100644
> --- a/include/qom/cpu.h
> +++ b/include/qom/cpu.h
> @@ -663,6 +663,18 @@ void run_on_cpu(CPUState *cpu, run_on_cpu_func func,
> void *data);
> void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data);
>
> /**
> + * async_safe_run_on_cpu:
> + * @cpu: The vCPU to run on.
> + * @func: The function to be executed.
> + * @data: Data to pass to the function.
> + *
> + * Schedules the function @func for execution on the vCPU @cpu
> asynchronously,
> + * while all other vCPUs are sleeping. @func is called with the CPU list
> lock
> + * taken (and for system emulation the BQL); any other lock can be taken
> safely.
> + */
> +void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, void *data);
> +
> +/**
> * qemu_get_cpu:
> * @index: The CPUState@cpu_index value of the CPU to obtain.
> *
I used the following diff on top(as suggested by bonzini) to fix a deadlock I
was seeing while testing.
Fix deadlock caused by holding BQL for safe work
Suggested-by: Paolo Bonzini <pbonz...@redhat.com>
Signed-off-by: Pranith Kumar <bobby.pr...@gmail.com>
---
cpus-common.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/cpus-common.c b/cpus-common.c
index 443617a..579917f 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -18,6 +18,7 @@
*/
#include "qemu/osdep.h"
+#include "qemu/main-loop.h"
#include "cpu.h"
#include "sysemu/cpus.h"
#include "exec/memory-internal.h"
@@ -269,9 +270,11 @@ static void async_safe_run_on_cpu_fn(CPUState *cpu, void
*data)
{
SafeWorkItem *w = data;
+ qemu_mutex_unlock_iothread();
start_exclusive();
w->func(cpu, w->data);
end_exclusive();
+ qemu_mutex_lock_iothread();
g_free(w);
}
--
Pranith
