[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH v2 7/9] cpus: Introduce qemu_mutex_unlock_iothread_prepare()

From: David Hildenbrand
Subject: Re: [PATCH v2 7/9] cpus: Introduce qemu_mutex_unlock_iothread_prepare()
Date: Wed, 28 Jul 2021 14:11:47 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0

On 27.07.21 18:08, Peter Xu wrote:
On Tue, Jul 27, 2021 at 02:59:26PM +0200, David Hildenbrand wrote:
On 23.07.21 21:34, Peter Xu wrote:
The prepare function before unlocking BQL.  There're only three places that can
release the BQL: unlock(), cond_wait() or cond_timedwait().

Signed-off-by: Peter Xu <peterx@redhat.com>
   softmmu/cpus.c | 7 +++++++
   1 file changed, 7 insertions(+)

diff --git a/softmmu/cpus.c b/softmmu/cpus.c
index 9131f77f87..6085f8edbe 100644
--- a/softmmu/cpus.c
+++ b/softmmu/cpus.c
@@ -66,6 +66,10 @@
   static QemuMutex qemu_global_mutex;
+static void qemu_mutex_unlock_iothread_prepare(void)
   bool cpu_is_stopped(CPUState *cpu)
       return cpu->stopped || !runstate_is_running();
@@ -523,16 +527,19 @@ void qemu_mutex_unlock_iothread(void)
       iothread_locked = false;
+    qemu_mutex_unlock_iothread_prepare();
   void qemu_cond_wait_iothread(QemuCond *cond)
+    qemu_mutex_unlock_iothread_prepare();
       qemu_cond_wait(cond, &qemu_global_mutex);
   void qemu_cond_timedwait_iothread(QemuCond *cond, int ms)
+    qemu_mutex_unlock_iothread_prepare();
       qemu_cond_timedwait(cond, &qemu_global_mutex, ms);

I'd squash this patch into the next one.

I don't quite like the function name, but don't really have a better
suggestion .... maybe qemu_mutex_might_unlock_iothread(), similar to
might_sleep() or might_fault() in the kernel. (although here it's pretty
clear and not a "might"; could be useful in other context where we might
conditionally unlock the BQL at some point in the future, though)

Yes, IMHO "might" describes a capability of doing something, here it's not
(this one should only be called right before releasing bql, not within any
context of having some capability).  The other option I thought was "pre" but
it will be just a short version of "prepare".

Let me know if you have a better suggestion on naming. :) Otherwise I'll keep
the naming, squash this patch into the next and keep your r-b for that.

Fine with me :)


David / dhildenb

reply via email to

[Prev in Thread] Current Thread [Next in Thread]