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Subject: Re: [PATCH] blk-iocost: Fix systemtap error on iocost_ioc_vrate_adj
To:     Waiman Long <longman@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, Tejun Heo <tj@kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        Ming Lei <ming.lei@redhat.com>
References: <20200421130755.18370-1-longman@redhat.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <f4ba2d62-993e-9da3-9adb-4049bda6ba63@kernel.dk>
Date:   Tue, 21 Apr 2020 09:50:16 -0600
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On 4/21/20 7:07 AM, Waiman Long wrote:
> Systemtap 4.2 is unable to correctly interpret the "u32 (*missed_ppm)[2]"
> argument of the iocost_ioc_vrate_adj trace entry defined in
> include/trace/events/iocost.h leading to the following error:
> 
>   /tmp/stapAcz0G0/stap_c89c58b83cea1724e26395efa9ed4939_6321_aux_6.c:78:8:
>   error: expected ‘;’, ‘,’ or ‘)’ before ‘*’ token
>    , u32[]* __tracepoint_arg_missed_ppm
> 
> That argument type is indeed rather complex and hard to read. Looking
> at block/blk-iocost.c. It is just a 2-entry u32 array. By simplifying
> the argument to a simple "u32 *missed_ppm" and adjusting the trace
> entry accordingly, the compilation error was gone.

Applied, thanks.

-- 
Jens Axboe