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Date:   Thu, 19 Mar 2020 17:26:40 -0700
From:   Bjorn Andersson <bjorn.andersson@linaro.org>
To:     Mike Tipton <mdtipton@codeaurora.org>
Cc:     georgi.djakov@linaro.org, agross@kernel.org,
        linux-pm@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] interconnect: qcom: Fix uninitialized tcs_cmd::wait
Message-ID: <20200320002640.GC458947@yoga>
References: <20200319231021.18108-1-mdtipton@codeaurora.org>
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On Thu 19 Mar 16:10 PDT 2020, Mike Tipton wrote:

> Currently, if tcs_cmd_gen is called with commit=false, then
> tcs_cmd::wait is left uninitialized. Since the tcs_cmd structures passed
> to this function aren't zero-initialized, then we're left with random
> wait values. This results in waiting for completion for more commands
> than is necessary, depending on what's on the stack at the time.
> 
> Removing the unnecessary if-condition fixes this, but add an explicit
> memset of the tcs_cmd structure as well to ensure predictable behavior
> if more tcs_cmd members are added in the future.
> 
> Fixes: 976daac4a1c5 ("interconnect: qcom: Consolidate interconnect RPMh support")
> Signed-off-by: Mike Tipton <mdtipton@codeaurora.org>

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

> ---
>  drivers/interconnect/qcom/bcm-voter.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/interconnect/qcom/bcm-voter.c b/drivers/interconnect/qcom/bcm-voter.c
> index 2adfde8cdf19..2a11a63e7217 100644
> --- a/drivers/interconnect/qcom/bcm-voter.c
> +++ b/drivers/interconnect/qcom/bcm-voter.c
> @@ -96,6 +96,8 @@ static inline void tcs_cmd_gen(struct tcs_cmd *cmd, u64 vote_x, u64 vote_y,
>  	if (!cmd)
>  		return;
>  
> +	memset(cmd, 0, sizeof(*cmd));
> +
>  	if (vote_x == 0 && vote_y == 0)
>  		valid = false;
>  
> @@ -112,8 +114,7 @@ static inline void tcs_cmd_gen(struct tcs_cmd *cmd, u64 vote_x, u64 vote_y,
>  	 * Set the wait for completion flag on command that need to be completed
>  	 * before the next command.
>  	 */
> -	if (commit)
> -		cmd->wait = true;
> +	cmd->wait = commit;
>  }
>  
>  static void tcs_list_gen(struct list_head *bcm_list, int bucket,
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project