From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Gustavo A. R. Silva" Subject: [PATCH] scsi: osst: Use struct_size() in kzalloc() Date: Wed, 19 Jun 2019 14:41:26 -0500 Message-ID: <20190619194126.GA3069@embeddedor> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: Willem Riede , "James E.J. Bottomley" , "Martin K. Petersen" Cc: osst-users@lists.sourceforge.net, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" List-Id: linux-scsi@vger.kernel.org One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example: struct osst_buffer { ... struct scatterlist sg[1]; /* MUST BE last item */ } ; i = sizeof(struct osst_buffer) + (osst_max_sg_segs - 1) * sizeof(struct scatterlist); instance = kzalloc(i, GFP_KERNEL); Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper: instance = kzalloc(struct_size(instance, sg, count), GFP_KERNEL); Notice that, in this case, variable i is not necessary, hence it is removed. This code was detected with the help of Coccinelle. Signed-off-by: Gustavo A. R. Silva --- drivers/scsi/osst.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/scsi/osst.c b/drivers/scsi/osst.c index 815bb4097c1b..a11455a7e6bf 100644 --- a/drivers/scsi/osst.c +++ b/drivers/scsi/osst.c @@ -5307,7 +5307,6 @@ static long osst_compat_ioctl(struct file * file, unsigned int cmd_in, unsigned /* Try to allocate a new tape buffer skeleton. Caller must not hold os_scsi_tapes_lock */ static struct osst_buffer * new_tape_buffer( int from_initialization, int need_dma, int max_sg ) { - int i; gfp_t priority; struct osst_buffer *tb; @@ -5316,8 +5315,7 @@ static struct osst_buffer * new_tape_buffer( int from_initialization, int need_d else priority = GFP_KERNEL; - i = sizeof(struct osst_buffer) + (osst_max_sg_segs - 1) * sizeof(struct scatterlist); - tb = kzalloc(i, priority); + tb = kzalloc(struct_size(tb, sg, osst_max_sg_segs - 1), priority); if (!tb) { printk(KERN_NOTICE "osst :I: Can't allocate new tape buffer.\n"); return NULL; -- 2.21.0