-----邮件原件-----
发件人: dev [off-list ref] 代表 Jerin Jacob
发送时间: Thursday, October 28, 2021 3:02 PM
收件人: Feifei Wang [off-list ref]
抄送: Honnappa Nagarahalli [off-list ref]; dpdk-dev
[off-list ref]; nd [off-list ref]; Ananyev, Konstantin
[off-list ref]; Stephen Hemminger
[off-list ref]; David Marchand
[off-list ref]; thomas@monjalon.net; Mattias Rönnblom
[off-list ref]; Ruifeng Wang [off-list ref]
主题: Re: [dpdk-dev] [PATCH v7 3/5] eal: use wait event scheme for mcslock

On Thu, Oct 28, 2021 at 12:27 PM Feifei Wang [off-list ref]
wrote:

quoted

Instead of polling for mcslock to be updated, use wait event scheme
for this case.

Furthermore, use 'uintptr_t *' is for different size of pointer in
32/64 bits architecture.

And define a new pointer 'next' for the compilation error:
-------------------------------------------------------------------
'dereferencing type-punned pointer will break strict-aliasing rules'
-------------------------------------------------------------------

Signed-off-by: Feifei Wang <redacted>
Reviewed-by: Ruifeng Wang <redacted>
---
 lib/eal/include/generic/rte_mcslock.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/eal/include/generic/rte_mcslock.h

b/lib/eal/include/generic/rte_mcslock.h
index 34f33c64a5..d5b9b293cd 100644

--- a/lib/eal/include/generic/rte_mcslock.h
+++ b/lib/eal/include/generic/rte_mcslock.h

@@ -116,8 +116,9 @@ rte_mcslock_unlock(rte_mcslock_t **msl,

rte_mcslock_t *me)

quoted

                /* More nodes added to the queue by other CPUs.
                 * Wait until the next pointer is set.
                 */
-               while (__atomic_load_n(&me->next, __ATOMIC_RELAXED) ==

NULL)

quoted

-                       rte_pause();
+               uintptr_t *next = NULL;

It is going to update in the next line. Why explicit NULL assignment?

You are right, it is unnecessary to initialize it as NULL. I will update this.

quoted

+               next = (uintptr_t *)&me->next;
+               rte_wait_event(next, UINTPTR_MAX, ==, 0,
+ __ATOMIC_RELAXED);
        }

        /* Pass lock to next waiter. */
--
2.25.1