From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Shyti Subject: Re: Re: [PATCH -next] spi: s3c64xx: fix reference leak to master in s3c64xx_spi_remove() Date: Wed, 13 Jul 2016 17:34:13 +0900 Message-ID: <20160713083413.GK18237@samsunx.samsung> References: <1468321722-16568-1-git-send-email-weiyj_lk@163.com> <20160713045030.GI18237@samsunx.samsung> <481c6f26.751d.155e2c1d661.Coremail.weiyj_lk@163.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Kukjin Kim , Krzysztof Kozlowski , Mark Brown , Wei Yongjun , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: weiyj Return-path: Content-disposition: inline In-reply-to: <481c6f26.751d.155e2c1d661.Coremail.weiyj_lk-9Onoh4P/yGk@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: 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 > > > >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 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html