From mboxrd@z Thu Jan  1 00:00:00 1970
From: andi.shyti@samsung.com (Andi Shyti)
Date: Wed, 13 Jul 2016 17:34:13 +0900
Subject: [PATCH -next] spi: s3c64xx: fix reference leak to master in
 s3c64xx_spi_remove()
In-Reply-To: <481c6f26.751d.155e2c1d661.Coremail.weiyj_lk@163.com>
References: <CGME20160712110926epcas1p13bbc88f5867d41d09d9b8c1172a7150b@epcas1p1.samsung.com>
 <1468321722-16568-1-git-send-email-weiyj_lk@163.com>
 <20160713045030.GI18237@samsunx.samsung>
 <481c6f26.751d.155e2c1d661.Coremail.weiyj_lk@163.com>
Message-ID: <20160713083413.GK18237@samsunx.samsung>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi Wei,

> >> Once a spi_master_get() call succeeds, we need an additional
> >> spi_master_put() call to free the memory, otherwise we will
> >> leak a reference to master. Fix by removing the unnecessary
> >> spi_master_get() call.
> >> 
> >> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
> >
> >The patch doesn't have anything wrong, but what you write in the
> >description is not what you are doing in the patch.
> >
> >There is no memory allocated in spi_master_get and nothing leaks.
> >Besides master's resources are managed, so that there would
> >not be any need to call spi_master_put().
> >
> >spi_master_put() has been, indeed, removed in this commit:
> >91800f0e90050a4db4c77e940796f501e02af8be.
> >
> 
> master allocated in spi_alloc_master() need device reference count to zero
> to be freed.
> 
> The call sequence spi_alloc_master/spi_register_master/spi_unregister_master
> is complete; it reduces the device reference count to zero, which results in
> device memory being freed.
> 
> In commit 91800f0e90050a4db4c77e940796f501e02af8be, 
> devm_spi_register_master() equal to spi_register_master() and auto call
> spi_unregister_master() when remove. But  remove spi_master_put()
> will cause the device reference count left no zero, since spi_master_get()
> is callled at the begin of remove function already.
> 
> So I think we should either remove the spi_master_get() or add spi_master_put()
> before return from remove function.

Yes, you are right, I missed this part :)

Thanks,
Andi