From mboxrd@z Thu Jan 1 00:00:00 1970 From: weiyj_lk@163.com (weiyj) Date: Wed, 13 Jul 2016 13:36:42 +0800 (CST) Subject: [PATCH -next] spi: s3c64xx: fix reference leak to master in s3c64xx_spi_remove() In-Reply-To: <20160713045030.GI18237@samsunx.samsung> References: <1468321722-16568-1-git-send-email-weiyj_lk@163.com> <20160713045030.GI18237@samsunx.samsung> Message-ID: <481c6f26.751d.155e2c1d661.Coremail.weiyj_lk@163.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Andi, At 2016-07-13 12:50:30, "Andi Shyti" wrote: >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. Regards, Yongjun Wei