linux-kernel - Re: [PATCH 5/6] mailbox: pcc: Initialize SHMEM before binding the channel with the client

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Message-ID: <ceb9f28b-c935-476b-bd67-a5a9da9989f6@huawei.com>
Date: Mon, 20 Oct 2025 12:15:38 +0800
From: "lihuisong (C)" <lihuisong@...wei.com>
To: Sudeep Holla <sudeep.holla@....com>, <linux-acpi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: Adam Young <admiyo@...amperecomputing.com>, Robbie King
	<robbiek@...ghtlabs.com>, Jassi Brar <jassisinghbrar@...il.com>, "Cristian
 Marussi" <cristian.marussi@....com>
Subject: Re: [PATCH 5/6] mailbox: pcc: Initialize SHMEM before binding the
 channel with the client


在 2025/10/17 3:08, Sudeep Holla 写道:
> The PCC channel's shared memory region must be set up before the
> mailbox controller binds the channel with the client, as the binding
> process may trigger client operations like startup() that may rely on
> SHMEM being initialized.
>
> Reorder the setup sequence to ensure the shared memory is ready before
> binding. Initialize and map the PCC shared memory (SHMEM) prior to
> calling mbox_bind_client() so that clients never observe an uninitialized
> or NULL SHMEM during bind-time callbacks or early use in startup().
>
> This makes the PCC mailbox channel bring-up order consistent and
> eliminates a race between SHMEM setup and client binding.

I don't think this race exists. The above reason is enough.

This patch should be for patch 6/6, right?

>
> This will be needed in channel startup to clear/acknowledge any pending
> interrupts before enabling them.
>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
Acked-by: lihuisong@...wei.com
> ---
>   drivers/mailbox/pcc.c | 18 ++++++++++--------
>   1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index 33bd2d05704b..2829ec51b47f 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -378,18 +378,20 @@ pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)

>