Re: [PATCH] PM / OPP: Protect updates to list_dev with mutex

Stephen Boyd
2015-11-04T22:11:29Z

On 10/30, Viresh Kumar wrote:
> dev_opp_list_lock is used everywhere to protect device and OPP lists,
> but dev_pm_opp_set_sharing_cpus() is missed somehow. And instead we used
> rcu-lock, which wouldn't help here as we are adding a new list_dev.
>
> This also fixes a problem where we have called kzalloc(..., GFP_KERNEL)
> from within rcu-lock, which isn't allowed as kzalloc can sleep when
> called with GFP_KERNEL.
>
> With CONFIG_DEBUG_ATOMIC_SLEEP set, we will see the caller vomiting.
>
> Fixes: 8d4d4e98acd6 ("PM / OPP: Add helpers for initializing CPU OPPs")
> Reported-by: Michael Turquette <mturquette@baylibre.com>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---

Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>

I assume some other patch will come to fix the comment and/or add
the lockdep check.

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