fork()ed processes currently start with
current_cpu->in_exclusive_context set, which is, strictly speaking, not
correct, but does not cause problems (even assertion failures).

With one of the next patches, the code begins to rely on this value, so
fix it by always calling end_exclusive() in fork_end().

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 linux-user/main.c    | 10 ++++++----
 linux-user/syscall.c |  1 +
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/linux-user/main.c b/linux-user/main.c
index 4290651c3cf..4ff30ff9806 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -161,13 +161,15 @@ void fork_end(int child)
         }
         qemu_init_cpu_list();
         gdbserver_fork(thread_cpu);
-        /* qemu_init_cpu_list() takes care of reinitializing the
-         * exclusive state, so we don't need to end_exclusive() here.
-         */
     } else {
         cpu_list_unlock();
-        end_exclusive();
     }
+    /*
+     * qemu_init_cpu_list() reinitialized the child exclusive state, but we
+     * also need to keep current_cpu consistent, so call end_exclusive() for
+     * both child and parent.
+     */
+    end_exclusive();
 }
 
 __thread CPUState *thread_cpu;
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 1e868e9b0e2..a6c426d73cf 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -6752,6 +6752,7 @@ static int do_fork(CPUArchState *env, unsigned int flags, abi_ulong newsp,
             cpu_clone_regs_parent(env, flags);
             fork_end(0);
         }
+        g_assert(!cpu_in_exclusive_context(cpu));
     }
     return ret;
 }
-- 
2.39.1

Ilya Leoshkevich <iii@linux.ibm.com> writes:

> fork()ed processes currently start with
> current_cpu->in_exclusive_context set, which is, strictly speaking, not
> correct, but does not cause problems (even assertion failures).
>
> With one of the next patches, the code begins to rely on this value, so
> fix it by always calling end_exclusive() in fork_end().
>
> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro

On 2/13/23 02:52, Ilya Leoshkevich wrote:
> fork()ed processes currently start with
> current_cpu->in_exclusive_context set, which is, strictly speaking, not
> correct, but does not cause problems (even assertion failures).
> 
> With one of the next patches, the code begins to rely on this value, so
> fix it by always calling end_exclusive() in fork_end().
> 
> Signed-off-by: Ilya Leoshkevich<iii@linux.ibm.com>
> ---
>   linux-user/main.c    | 10 ++++++----
>   linux-user/syscall.c |  1 +
>   2 files changed, 7 insertions(+), 4 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~