From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michael Ellerman <mpe@ellerman.id.au>
Date: Mon, 14 Aug 2017 03:30:41 +0000
Subject: Re: [PATCH] powerpc/perf: double unlock bug in imc_common_cpuhp_mem_free()
Message-Id: <87bmnisu5a.fsf@concordia.ellerman.id.au>
List-Id: <kernel-janitors.vger.kernel.org>
References: <20170811200541.qlxcpp3og33sdki3@mwanda>
In-Reply-To: <20170811200541.qlxcpp3og33sdki3@mwanda>
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To: Dan Carpenter <dan.carpenter@oracle.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Anju T Sudhakar <anju@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>, Madhavan Srinivasan <maddy@linux.vnet.ibm.com>, Hemant Kumar <hemant@linux.vnet.ibm.com>, linuxppc-dev@lists.ozlabs.org, kernel-janitors@vger.kernel.org

Dan Carpenter <dan.carpenter@oracle.com> writes:

> There is a typo so we call unlock instead of lock.
>
> Fixes: 885dcd709ba9 ("powerpc/perf: Add nest IMC PMU support")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> I also don't understand how the &nest_imc_refc[node_id].lock works.  Why
> can't we use ref->lock everywhere?  They seem equivalent, and my static
> checker complains if we call the same lock different names.

That looks like a bug to me, ie. we should always use ref.

Maddy?

cheers

> diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
> index 46cd912af060..52017f6eafd9 100644
> --- a/arch/powerpc/perf/imc-pmu.c
> +++ b/arch/powerpc/perf/imc-pmu.c
> @@ -1124,7 +1124,7 @@ static void cleanup_all_thread_imc_memory(void)
>  static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr)
>  {
>  	if (pmu_ptr->domain = IMC_DOMAIN_NEST) {
> -		mutex_unlock(&nest_init_lock);
> +		mutex_lock(&nest_init_lock);
>  		if (nest_pmus = 1) {
>  			cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE);
>  			kfree(nest_imc_refc);