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From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, David Hildenbrand <david@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Hillf Danton <hdanton@sina.com>, Michal Hocko <mhocko@suse.com>,
	Matthew Wilcox <willy@infradead.org>,
	Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Minchan Kim <minchan@kernel.org>,
	huang ying <huang.ying.caritas@gmail.com>
Subject: [PATCH v1 3/3] mm/vmalloc: remove vwrite()
Date: Wed, 24 Mar 2021 11:23:51 +0100	[thread overview]
Message-ID: <20210324102351.6932-4-david@redhat.com> (raw)
In-Reply-To: <20210324102351.6932-1-david@redhat.com>

The last user (/dev/kmem) is gone. Let's drop it.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: huang ying <huang.ying.caritas@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 include/linux/vmalloc.h |   1 -
 mm/nommu.c              |  10 ----
 mm/vmalloc.c            | 116 +---------------------------------------
 3 files changed, 1 insertion(+), 126 deletions(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 390af680e916..9c1b17c7dd95 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -200,7 +200,6 @@ static inline void set_vm_flush_reset_perms(void *addr)
 
 /* for /proc/kcore */
 extern long vread(char *buf, char *addr, unsigned long count);
-extern long vwrite(char *buf, char *addr, unsigned long count);
 
 /*
  *	Internals.  Dont't use..
diff --git a/mm/nommu.c b/mm/nommu.c
index 5c9ab799c0e6..85a3a68dffb6 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -210,16 +210,6 @@ long vread(char *buf, char *addr, unsigned long count)
 	return count;
 }
 
-long vwrite(char *buf, char *addr, unsigned long count)
-{
-	/* Don't allow overflow */
-	if ((unsigned long) addr + count < count)
-		count = -(unsigned long) addr;
-
-	memcpy(addr, buf, count);
-	return count;
-}
-
 /*
  *	vmalloc  -  allocate virtually contiguous memory
  *
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ccb405b82581..434f61c9c466 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2802,10 +2802,7 @@ static int aligned_vread(char *buf, char *addr, unsigned long count)
 		 * kmap() and get small overhead in this access function.
 		 */
 		if (p) {
-			/*
-			 * we can expect USER0 is not used (see vread/vwrite's
-			 * function description)
-			 */
+			/* We can expect USER0 is not used -- see vread() */
 			void *map = kmap_atomic(p);
 			memcpy(buf, map + offset, length);
 			kunmap_atomic(map);
@@ -2820,43 +2817,6 @@ static int aligned_vread(char *buf, char *addr, unsigned long count)
 	return copied;
 }
 
-static int aligned_vwrite(char *buf, char *addr, unsigned long count)
-{
-	struct page *p;
-	int copied = 0;
-
-	while (count) {
-		unsigned long offset, length;
-
-		offset = offset_in_page(addr);
-		length = PAGE_SIZE - offset;
-		if (length > count)
-			length = count;
-		p = vmalloc_to_page(addr);
-		/*
-		 * To do safe access to this _mapped_ area, we need
-		 * lock. But adding lock here means that we need to add
-		 * overhead of vmalloc()/vfree() calles for this _debug_
-		 * interface, rarely used. Instead of that, we'll use
-		 * kmap() and get small overhead in this access function.
-		 */
-		if (p) {
-			/*
-			 * we can expect USER0 is not used (see vread/vwrite's
-			 * function description)
-			 */
-			void *map = kmap_atomic(p);
-			memcpy(map + offset, buf, length);
-			kunmap_atomic(map);
-		}
-		addr += length;
-		buf += length;
-		copied += length;
-		count -= length;
-	}
-	return copied;
-}
-
 /**
  * vread() - read vmalloc area in a safe way.
  * @buf:     buffer for reading data
@@ -2936,80 +2896,6 @@ long vread(char *buf, char *addr, unsigned long count)
 	return buflen;
 }
 
-/**
- * vwrite() - write vmalloc area in a safe way.
- * @buf:      buffer for source data
- * @addr:     vm address.
- * @count:    number of bytes to be read.
- *
- * This function checks that addr is a valid vmalloc'ed area, and
- * copy data from a buffer to the given addr. If specified range of
- * [addr...addr+count) includes some valid address, data is copied from
- * proper area of @buf. If there are memory holes, no copy to hole.
- * IOREMAP area is treated as memory hole and no copy is done.
- *
- * If [addr...addr+count) doesn't includes any intersects with alive
- * vm_struct area, returns 0. @buf should be kernel's buffer.
- *
- * Note: In usual ops, vwrite() is never necessary because the caller
- * should know vmalloc() area is valid and can use memcpy().
- * This is for routines which have to access vmalloc area without
- * any information, as /dev/kmem.
- *
- * Return: number of bytes for which addr and buf should be
- * increased (same number as @count) or %0 if [addr...addr+count)
- * doesn't include any intersection with valid vmalloc area
- */
-long vwrite(char *buf, char *addr, unsigned long count)
-{
-	struct vmap_area *va;
-	struct vm_struct *vm;
-	char *vaddr;
-	unsigned long n, buflen;
-	int copied = 0;
-
-	/* Don't allow overflow */
-	if ((unsigned long) addr + count < count)
-		count = -(unsigned long) addr;
-	buflen = count;
-
-	spin_lock(&vmap_area_lock);
-	list_for_each_entry(va, &vmap_area_list, list) {
-		if (!count)
-			break;
-
-		if (!va->vm)
-			continue;
-
-		vm = va->vm;
-		vaddr = (char *) vm->addr;
-		if (addr >= vaddr + get_vm_area_size(vm))
-			continue;
-		while (addr < vaddr) {
-			if (count == 0)
-				goto finished;
-			buf++;
-			addr++;
-			count--;
-		}
-		n = vaddr + get_vm_area_size(vm) - addr;
-		if (n > count)
-			n = count;
-		if (!(vm->flags & VM_IOREMAP)) {
-			aligned_vwrite(buf, addr, n);
-			copied++;
-		}
-		buf += n;
-		addr += n;
-		count -= n;
-	}
-finished:
-	spin_unlock(&vmap_area_lock);
-	if (!copied)
-		return 0;
-	return buflen;
-}
-
 /**
  * remap_vmalloc_range_partial - map vmalloc pages to userspace
  * @vma:		vma to cover
-- 
2.29.2



  parent reply	other threads:[~2021-03-24 10:25 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-24 10:23 [PATCH v1 0/3] drivers/char: remove /dev/kmem for good David Hildenbrand
2021-03-24 10:23 ` [PATCH v1 1/3] " David Hildenbrand
2021-03-24 10:23 ` [PATCH v1 2/3] mm: remove xlate_dev_kmem_ptr() David Hildenbrand
2021-03-24 10:23 ` David Hildenbrand [this message]
2021-03-24 19:24 ` [PATCH v1 0/3] drivers/char: remove /dev/kmem for good Andrew Morton
2021-03-24 22:58   ` Balbir Singh
2021-03-25  6:46     ` Greg Kroah-Hartman
2021-03-25  6:46   ` Greg Kroah-Hartman
2021-03-31 15:18   ` Enrico Weigelt, metux IT consult
2021-03-24 20:14 ` Michal Hocko

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