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[PATCH v3 2/4] cpus: Make {start,end}_exclusive() recursive
From: |
Ilya Leoshkevich |
Subject: |
[PATCH v3 2/4] cpus: Make {start,end}_exclusive() recursive |
Date: |
Mon, 13 Feb 2023 21:57:57 +0100 |
Currently dying to one of the core_dump_signal()s deadlocks, because
dump_core_and_abort() calls start_exclusive() two times: first via
stop_all_tasks(), and then via preexit_cleanup() ->
qemu_plugin_user_exit().
There are a number of ways to solve this: resume after dumping core;
check cpu_in_exclusive_context() in qemu_plugin_user_exit(); or make
{start,end}_exclusive() recursive. Pick the last option, since it's
the most straightforward one.
Fixes: da91c1920242 ("linux-user: Clean up when exiting due to a signal")
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
cpus-common.c | 12 ++++++++++--
include/hw/core/cpu.h | 4 ++--
2 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/cpus-common.c b/cpus-common.c
index 793364dc0ed..39f355de989 100644
--- a/cpus-common.c
+++ b/cpus-common.c
@@ -192,6 +192,11 @@ void start_exclusive(void)
CPUState *other_cpu;
int running_cpus;
+ if (current_cpu->exclusive_context_count) {
+ current_cpu->exclusive_context_count++;
+ return;
+ }
+
qemu_mutex_lock(&qemu_cpu_list_lock);
exclusive_idle();
@@ -219,13 +224,16 @@ void start_exclusive(void)
*/
qemu_mutex_unlock(&qemu_cpu_list_lock);
- current_cpu->in_exclusive_context = true;
+ current_cpu->exclusive_context_count = 1;
}
/* Finish an exclusive operation. */
void end_exclusive(void)
{
- current_cpu->in_exclusive_context = false;
+ current_cpu->exclusive_context_count--;
+ if (current_cpu->exclusive_context_count) {
+ return;
+ }
qemu_mutex_lock(&qemu_cpu_list_lock);
qatomic_set(&pending_cpus, 0);
diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index 2417597236b..671f041bec6 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -349,7 +349,7 @@ struct CPUState {
bool unplug;
bool crash_occurred;
bool exit_request;
- bool in_exclusive_context;
+ int exclusive_context_count;
uint32_t cflags_next_tb;
/* updates protected by BQL */
uint32_t interrupt_request;
@@ -758,7 +758,7 @@ void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func
func, run_on_cpu_data
*/
static inline bool cpu_in_exclusive_context(const CPUState *cpu)
{
- return cpu->in_exclusive_context;
+ return cpu->exclusive_context_count;
}
/**
--
2.39.1