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cpus: Make {start,end}_exclusive() recursive 

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: da91c19202 ("linux-user: Clean up when exiting due to a signal")
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20230214140829.45392-3-iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Ilya Leoshkevich 2023-02-14 15:08:27 +01:00 committed by Richard Henderson
parent 7de0816f69
commit df8a688032
2 changed files with 12 additions and 4 deletions
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12
cpus-common.c
View File

@ -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);

4
include/hw/core/cpu.h
View File

@ -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;
}
/**