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* [PATCH net-next] svcrdma: Use struct_size() in kmalloc()
@ 2019-01-15 21:11 Gustavo A. R. Silva
  2019-01-15 21:49 ` Chuck Lever
  0 siblings, 1 reply; 4+ messages in thread
From: Gustavo A. R. Silva @ 2019-01-15 21:11 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, J. Bruce Fields, Jeff Layton,
	David S. Miller
  Cc: linux-nfs, netdev, linux-kernel, Gustavo A. R. Silva

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 foo {
    int stuff;
    struct boo entry[];
};

instance = kmalloc(sizeof(struct foo) + count * sizeof(struct boo), GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 net/sunrpc/xprtrdma/svc_rdma_rw.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_rdma_rw.c
index dc1951759a8e..cad37c2122ab 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_rw.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c
@@ -64,8 +64,7 @@ svc_rdma_get_rw_ctxt(struct svcxprt_rdma *rdma, unsigned int sges)
 		spin_unlock(&rdma->sc_rw_ctxt_lock);
 	} else {
 		spin_unlock(&rdma->sc_rw_ctxt_lock);
-		ctxt = kmalloc(sizeof(*ctxt) +
-			       SG_CHUNK_SIZE * sizeof(struct scatterlist),
+		ctxt = kmalloc(struct_size(ctxt, rw_first_sgl, SG_CHUNK_SIZE),
 			       GFP_KERNEL);
 		if (!ctxt)
 			goto out;
-- 
2.20.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH net-next] svcrdma: Use struct_size() in kmalloc()
  2019-01-15 21:11 [PATCH net-next] svcrdma: Use struct_size() in kmalloc() Gustavo A. R. Silva
@ 2019-01-15 21:49 ` Chuck Lever
  2019-01-15 21:53   ` Gustavo A. R. Silva
  2019-01-16 23:07   ` Bruce Fields
  0 siblings, 2 replies; 4+ messages in thread
From: Chuck Lever @ 2019-01-15 21:49 UTC (permalink / raw)
  To: Gustavo A. R. Silva
  Cc: Trond Myklebust, Anna Schumaker, Bruce Fields, Jeff Layton,
	David S. Miller, Linux NFS Mailing List, netdev, linux-kernel



On Jan 15, 2019, at 4:11 PM, Gustavo A. R. Silva <gustavo@embeddedor.com> wrote:

> 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 foo {
>    int stuff;
>    struct boo entry[];
> };
> 
> instance = kmalloc(sizeof(struct foo) + count * sizeof(struct boo), GFP_KERNEL);
> 
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
> 
> instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Reviewed-by: Chuck Lever <chuck.lever@oracle.com>


> ---
> net/sunrpc/xprtrdma/svc_rdma_rw.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_rdma_rw.c
> index dc1951759a8e..cad37c2122ab 100644
> --- a/net/sunrpc/xprtrdma/svc_rdma_rw.c
> +++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c
> @@ -64,8 +64,7 @@ svc_rdma_get_rw_ctxt(struct svcxprt_rdma *rdma, unsigned int sges)
> 		spin_unlock(&rdma->sc_rw_ctxt_lock);
> 	} else {
> 		spin_unlock(&rdma->sc_rw_ctxt_lock);
> -		ctxt = kmalloc(sizeof(*ctxt) +
> -			       SG_CHUNK_SIZE * sizeof(struct scatterlist),
> +		ctxt = kmalloc(struct_size(ctxt, rw_first_sgl, SG_CHUNK_SIZE),
> 			       GFP_KERNEL);
> 		if (!ctxt)
> 			goto out;
> -- 
> 2.20.1

--
Chuck Lever




^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH net-next] svcrdma: Use struct_size() in kmalloc()
  2019-01-15 21:49 ` Chuck Lever
@ 2019-01-15 21:53   ` Gustavo A. R. Silva
  2019-01-16 23:07   ` Bruce Fields
  1 sibling, 0 replies; 4+ messages in thread
From: Gustavo A. R. Silva @ 2019-01-15 21:53 UTC (permalink / raw)
  To: Chuck Lever
  Cc: Trond Myklebust, Anna Schumaker, Bruce Fields, Jeff Layton,
	David S. Miller, Linux NFS Mailing List, netdev, linux-kernel



On 1/15/19 3:49 PM, Chuck Lever wrote:
> 
> 
> On Jan 15, 2019, at 4:11 PM, Gustavo A. R. Silva <gustavo@embeddedor.com> wrote:
> 
>> 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 foo {
>>     int stuff;
>>     struct boo entry[];
>> };
>>
>> instance = kmalloc(sizeof(struct foo) + count * sizeof(struct boo), GFP_KERNEL);
>>
>> Instead of leaving these open-coded and prone to type mistakes, we can
>> now use the new struct_size() helper:
>>
>> instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);
>>
>> This code was detected with the help of Coccinelle.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> 
> Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
> 

Thank you, Chuck.
--
Gustavo

> 
>> ---
>> net/sunrpc/xprtrdma/svc_rdma_rw.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_rdma_rw.c
>> index dc1951759a8e..cad37c2122ab 100644
>> --- a/net/sunrpc/xprtrdma/svc_rdma_rw.c
>> +++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c
>> @@ -64,8 +64,7 @@ svc_rdma_get_rw_ctxt(struct svcxprt_rdma *rdma, unsigned int sges)
>> 		spin_unlock(&rdma->sc_rw_ctxt_lock);
>> 	} else {
>> 		spin_unlock(&rdma->sc_rw_ctxt_lock);
>> -		ctxt = kmalloc(sizeof(*ctxt) +
>> -			       SG_CHUNK_SIZE * sizeof(struct scatterlist),
>> +		ctxt = kmalloc(struct_size(ctxt, rw_first_sgl, SG_CHUNK_SIZE),
>> 			       GFP_KERNEL);
>> 		if (!ctxt)
>> 			goto out;
>> -- 
>> 2.20.1
> 
> --
> Chuck Lever
> 
> 
> 

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH net-next] svcrdma: Use struct_size() in kmalloc()
  2019-01-15 21:49 ` Chuck Lever
  2019-01-15 21:53   ` Gustavo A. R. Silva
@ 2019-01-16 23:07   ` Bruce Fields
  1 sibling, 0 replies; 4+ messages in thread
From: Bruce Fields @ 2019-01-16 23:07 UTC (permalink / raw)
  To: Chuck Lever
  Cc: Gustavo A. R. Silva, Trond Myklebust, Anna Schumaker,
	Jeff Layton, David S. Miller, Linux NFS Mailing List, netdev,
	linux-kernel

On Tue, Jan 15, 2019 at 04:49:16PM -0500, Chuck Lever wrote:
> 
> 
> On Jan 15, 2019, at 4:11 PM, Gustavo A. R. Silva <gustavo@embeddedor.com> wrote:
> 
> > 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 foo {
> >    int stuff;
> >    struct boo entry[];
> > };
> > 
> > instance = kmalloc(sizeof(struct foo) + count * sizeof(struct boo), GFP_KERNEL);
> > 
> > Instead of leaving these open-coded and prone to type mistakes, we can
> > now use the new struct_size() helper:
> > 
> > instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);
> > 
> > This code was detected with the help of Coccinelle.
> > 
> > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> 
> Reviewed-by: Chuck Lever <chuck.lever@oracle.com>

Thanks, applying for 5.1.--b.

> 
> 
> > ---
> > net/sunrpc/xprtrdma/svc_rdma_rw.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_rdma_rw.c
> > index dc1951759a8e..cad37c2122ab 100644
> > --- a/net/sunrpc/xprtrdma/svc_rdma_rw.c
> > +++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c
> > @@ -64,8 +64,7 @@ svc_rdma_get_rw_ctxt(struct svcxprt_rdma *rdma, unsigned int sges)
> > 		spin_unlock(&rdma->sc_rw_ctxt_lock);
> > 	} else {
> > 		spin_unlock(&rdma->sc_rw_ctxt_lock);
> > -		ctxt = kmalloc(sizeof(*ctxt) +
> > -			       SG_CHUNK_SIZE * sizeof(struct scatterlist),
> > +		ctxt = kmalloc(struct_size(ctxt, rw_first_sgl, SG_CHUNK_SIZE),
> > 			       GFP_KERNEL);
> > 		if (!ctxt)
> > 			goto out;
> > -- 
> > 2.20.1
> 
> --
> Chuck Lever
> 
> 

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-01-16 23:07 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2019-01-15 21:11 [PATCH net-next] svcrdma: Use struct_size() in kmalloc() Gustavo A. R. Silva
2019-01-15 21:49 ` Chuck Lever
2019-01-15 21:53   ` Gustavo A. R. Silva
2019-01-16 23:07   ` Bruce Fields

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