Subject: Re: [PATCH] vhost-scsi: Depend on NET for memcpy_fromiovec

From: Rusty Russell <[email-masked]>
Date: Fri, 17 May 2013 16:25:49 +0930

Randy Dunlap <[email-masked]> writes:
> On 05/16/13 16:42, Rusty Russell wrote:
>> Joe Perches <[email-masked]> writes:
>>> On Thu, 2013-05-16 at 13:04 +0930, Rusty Russell wrote:
>>>> Asias He <[email-masked]> writes:
>>>>> On Wed, May 15, 2013 at 02:47:53PM +0930, Rusty Russell wrote:
>>> []
>>>>> Other users are using memcpy_fromiovec and friends outside net. It seems
>>>>> a good idea to put it in a util library. e.g.  crypto/algif_skcipher.c
>>>>> which also depends on NET for it.
>>>
>>> []
>>>> Subject: Hoist memcpy_fromiovec into lib/
>>>
>>> You'll need the "friends" memcpy_toiovec too.
>>>
>>> $ git grep -E \bmemcpy\w+iovec\w*"
>>> crypto/algif_hash.c:    err = memcpy_toiovec(msg->msg_iov, ctx->result, len);
>>> crypto/algif_skcipher.c:                        err = memcpy_fromiovec(page_address(sg_page(sg)) +
>>> crypto/algif_skcipher.c:                        err = memcpy_fromiovec(page_address(sg_page(sg + i)),
>>> drivers/dma/iovlock.c:#include <net/tcp.h> /* for memcpy_toiovec */
>>> drivers/dma/iovlock.c:          return memcpy_toiovec(iov, kdata, len);
>>> drivers/dma/iovlock.c:          err = memcpy_toiovec(iov, vaddr + offset, len);
>>> drivers/isdn/mISDN/socket.c:    if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) {
>>> drivers/misc/vmw_vmci/vmci_queue_pair.c:                        err = memcpy_fromiovec((u8 *)va + page_o
>>> drivers/misc/vmw_vmci/vmci_queue_pair.c:                        err = memcpy_toiovec(iov, (u8 *)va + pag
>> 
>> Fascinating.  These all indirectly depend on NET, so there's no problem
>> at the moment.  But it is a bit weird...
>> 
>> crypto/algif_hash.c: depends on CRYPTO_USER_API_HASH -> NET
>> crypto/algif_skcipher.c: depends on CRYPTO_USER_API_SKCIPHER -> NET
>> drivers/dma/iovlock.c: depends on NET_DMA -> NET
>> drivers/isdn/mISDN/socket.c: depends on MISDN -> ISDN -> NET
>> drivers/misc/vmw_vmci/vmci_queue_pair.c: depends on VMCI -> NET
>> 
>> Patch welcome.
>> 
>> Meanwhile, to avoid more bikeshedding I've put the patch I posted with
>> all acks in my fixes branch.  One cycle through linux-next, then
>> straight to Linus.
>> 
>
> I agree with whoever suggested that more be moved into /lib.
> E.g., drivers/misc/vmw_vmci/Kconfig uses "depends on NET" because the
> code there uses both memcpy_toiovec() and memcpy_fromiovec().
> See commit ID 6d4f0139d642c45411a47879325891ce2a7c164a.

(CC's trimmed).

You Acked that commit :(

At a glance, the only way to drive the vmw_vmci device is through
net/vmw_vsock/vmci_transport.c, so without NET it's useless?  But let's
keep it neat anyway.  This was compiletested with CONFIG_VMCI,
CONFIG_DMA_ENGINE and !CONFIG_NET.

Thanks,
Rusty.

From: Rusty Russell <[email-masked]>
Subject: [PATCH] Hoist memcpy_fromiovec/memcpy_toiovec into lib/

ERROR: "memcpy_fromiovec" [drivers/vhost/vhost_scsi.ko] undefined!

That function is only present with CONFIG_NET.  Turns out that
crypto/algif_skcipher.c also uses that outside net, but it actually
needs sockets anyway.

In addition, commit 6d4f0139d642c45411a47879325891ce2a7c164a added
CONFIG_NET dependency to CONFIG_VMCI for memcpy_toiovec, so hoist
that function and revert that commit too.

socket.h already include uio.h, so no callers *need* updating,
though I update the obvious ones.

Reported-by: Randy Dunlap <[email-masked]>
Acked-by: David S. Miller <[email-masked]>
Acked-by: Michael S. Tsirkin <[email-masked]>
Signed-off-by: Rusty Russell <[email-masked]>

diff --git a/drivers/dma/iovlock.c b/drivers/dma/iovlock.c
index bb48a57..6943deb66 100644
--- a/drivers/dma/iovlock.c
+++ b/drivers/dma/iovlock.c
@@ -28,7 +28,7 @@
 #include <linux/dmaengine.h>
 #include <linux/pagemap.h>
 #include <linux/slab.h>
-#include <net/tcp.h> /* for memcpy_toiovec */
+#include <linux/uio.h> /* for memcpy_toiovec */
 #include <asm/io.h>
 #include <asm/uaccess.h>
 
diff --git a/drivers/misc/vmw_vmci/Kconfig b/drivers/misc/vmw_vmci/Kconfig
index ea98f7e..39c2eca 100644
--- a/drivers/misc/vmw_vmci/Kconfig
+++ b/drivers/misc/vmw_vmci/Kconfig
@@ -4,7 +4,7 @@
 
 config VMWARE_VMCI
 	tristate "VMware VMCI Driver"
-	depends on X86 && PCI && NET
+	depends on X86 && PCI
 	help
 	  This is VMware's Virtual Machine Communication Interface.  It enables
 	  high-speed communication between host and guest in a virtual
diff --git a/drivers/misc/vmw_vmci/vmci_queue_pair.c b/drivers/misc/vmw_vmci/vmci_queue_pair.c
index d94245d..8ff2e5e 100644
--- a/drivers/misc/vmw_vmci/vmci_queue_pair.c
+++ b/drivers/misc/vmw_vmci/vmci_queue_pair.c
@@ -23,7 +23,7 @@
 #include <linux/pagemap.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
-#include <linux/socket.h>
+#include <linux/uio.h>
 #include <linux/wait.h>
 #include <linux/vmalloc.h>
 
diff --git a/include/linux/socket.h b/include/linux/socket.h
index 428c37a..33bf2df 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -305,7 +305,6 @@ struct ucred {
 
 extern void cred_to_ucred(struct pid *pid, const struct cred *cred, struct ucred *ucred);
 
-extern int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
 extern int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
 			       int offset, int len);
 extern int csum_partial_copy_fromiovecend(unsigned char *kdata, 
@@ -314,7 +313,6 @@ extern int csum_partial_copy_fromiovecend(unsigned char *kdata,
 					  unsigned int len, __wsum *csump);
 
 extern int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *address, int mode);
-extern int memcpy_toiovec(struct iovec *v, unsigned char *kdata, int len);
 extern int memcpy_toiovecend(const struct iovec *v, unsigned char *kdata,
 			     int offset, int len);
 extern int move_addr_to_kernel(void __user *uaddr, int ulen, struct sockaddr_storage *kaddr);
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 629aaf5..c55ce24 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -35,4 +35,7 @@ static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
 }
 
 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
+
+int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
+int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);
 #endif
diff --git a/lib/Makefile b/lib/Makefile
index e9c52e1..2377211 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -9,7 +9,7 @@ endif
 
 lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 rbtree.o radix-tree.o dump_stack.o timerqueue.o\
-	 idr.o int_sqrt.o extable.o \
+	 idr.o int_sqrt.o extable.o iovec.o \
 	 sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
 	 proportions.o flex_proportions.o prio_heap.o ratelimit.o show_mem.o \
 	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
diff --git a/lib/iovec.c b/lib/iovec.c
new file mode 100644
index 0000000..454baa8
--- /dev/null
+++ b/lib/iovec.c
@@ -0,0 +1,53 @@
+#include <linux/uaccess.h>
+#include <linux/export.h>
+#include <linux/uio.h>
+
+/*
+ *	Copy iovec to kernel. Returns -EFAULT on error.
+ *
+ *	Note: this modifies the original iovec.
+ */
+
+int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len)
+{
+	while (len > 0) {
+		if (iov->iov_len) {
+			int copy = min_t(unsigned int, len, iov->iov_len);
+			if (copy_from_user(kdata, iov->iov_base, copy))
+				return -EFAULT;
+			len -= copy;
+			kdata += copy;
+			iov->iov_base += copy;
+			iov->iov_len -= copy;
+		}
+		iov++;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(memcpy_fromiovec);
+
+/*
+ *	Copy kernel to iovec. Returns -EFAULT on error.
+ *
+ *	Note: this modifies the original iovec.
+ */
+
+int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len)
+{
+	while (len > 0) {
+		if (iov->iov_len) {
+			int copy = min_t(unsigned int, iov->iov_len, len);
+			if (copy_to_user(iov->iov_base, kdata, copy))
+				return -EFAULT;
+			kdata += copy;
+			len -= copy;
+			iov->iov_len -= copy;
+			iov->iov_base += copy;
+		}
+		iov++;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(memcpy_toiovec);
diff --git a/net/core/iovec.c b/net/core/iovec.c
index 7e7aeb0..de178e4 100644
--- a/net/core/iovec.c
+++ b/net/core/iovec.c
@@ -75,31 +75,6 @@ int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *a
 
 /*
  *	Copy kernel to iovec. Returns -EFAULT on error.
- *
- *	Note: this modifies the original iovec.
- */
-
-int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len)
-{
-	while (len > 0) {
-		if (iov->iov_len) {
-			int copy = min_t(unsigned int, iov->iov_len, len);
-			if (copy_to_user(iov->iov_base, kdata, copy))
-				return -EFAULT;
-			kdata += copy;
-			len -= copy;
-			iov->iov_len -= copy;
-			iov->iov_base += copy;
-		}
-		iov++;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL(memcpy_toiovec);
-
-/*
- *	Copy kernel to iovec. Returns -EFAULT on error.
  */
 
 int memcpy_toiovecend(const struct iovec *iov, unsigned char *kdata,
@@ -125,31 +100,6 @@ int memcpy_toiovecend(const struct iovec *iov, unsigned char *kdata,
 EXPORT_SYMBOL(memcpy_toiovecend);
 
 /*
- *	Copy iovec to kernel. Returns -EFAULT on error.
- *
- *	Note: this modifies the original iovec.
- */
-
-int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len)
-{
-	while (len > 0) {
-		if (iov->iov_len) {
-			int copy = min_t(unsigned int, len, iov->iov_len);
-			if (copy_from_user(kdata, iov->iov_base, copy))
-				return -EFAULT;
-			len -= copy;
-			kdata += copy;
-			iov->iov_base += copy;
-			iov->iov_len -= copy;
-		}
-		iov++;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL(memcpy_fromiovec);
-
-/*
  *	Copy iovec from kernel. Returns -EFAULT on error.
  */