Hi Linus,
Here is the same patch but remade (and re-looked-at and retested) against
2.3.99-pre7-2. It adds a rw spinlock vmlist_lock to guard access to vmlist
and makes use of it fs/proc/kcore.c (bug fix!) and in ipc/util.c
(optimization).
Please consider it.
Regards,
Tigran
diff -urN -X dontdiff linux/drivers/char/mem.c vmalloc/drivers/char/mem.c
--- linux/drivers/char/mem.c Wed Apr 12 09:09:20 2000
+++ vmalloc/drivers/char/mem.c Wed May 3 12:54:19 2000
@@ -231,7 +231,8 @@
{
unsigned long p = *ppos;
ssize_t read = 0;
- ssize_t virtr;
+ ssize_t virtr = 0;
+ char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
if (p < (unsigned long) high_memory) {
read = count;
@@ -258,11 +259,27 @@
count -= read;
}
- virtr = vread(buf, (char *)p, count);
- if (virtr < 0)
- return virtr;
- *ppos += p + virtr;
- return virtr + read;
+ kbuf = (char *)get_free_page(GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+ while (count > 0) {
+ int len = count;
+
+ if (len > PAGE_SIZE)
+ len = PAGE_SIZE;
+ len = vread(kbuf, (char *)p, len); /* always >= 0 */
+ if (len && copy_to_user(buf, kbuf, len)) {
+ free_page((unsigned long)kbuf);
+ return -EFAULT;
+ }
+ count -= len;
+ buf += len;
+ virtr += len;
+ p += len;
+ }
+ free_page((unsigned long)kbuf);
+ *ppos += p + virtr;
+ return virtr + read;
}
/*
diff -urN -X dontdiff linux/fs/proc/kcore.c vmalloc/fs/proc/kcore.c
--- linux/fs/proc/kcore.c Sun Feb 27 04:33:07 2000
+++ vmalloc/fs/proc/kcore.c Wed May 3 12:54:19 2000
@@ -315,13 +315,12 @@
size_t elf_buflen;
int num_vma;
- /* XXX we need to somehow lock vmlist between here
- * and after elf_kcore_store_hdr() returns.
- * For now assume that num_vma does not change (TA)
- */
+ read_lock(&vmlist_lock);
proc_root_kcore->size = size = get_kcore_size(&num_vma, &elf_buflen);
- if (buflen == 0 || *fpos >= size)
+ if (buflen == 0 || *fpos >= size) {
+ read_unlock(&vmlist_lock);
return 0;
+ }
/* trim buflen to not go beyond EOF */
if (buflen > size - *fpos)
@@ -335,10 +334,13 @@
if (buflen < tsz)
tsz = buflen;
elf_buf = kmalloc(elf_buflen, GFP_ATOMIC);
- if (!elf_buf)
+ if (!elf_buf) {
+ read_unlock(&vmlist_lock);
return -ENOMEM;
+ }
memset(elf_buf, 0, elf_buflen);
elf_kcore_store_hdr(elf_buf, num_vma, elf_buflen);
+ read_unlock(&vmlist_lock);
if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
kfree(elf_buf);
return -EFAULT;
@@ -352,7 +354,8 @@
/* leave now if filled buffer already */
if (buflen == 0)
return acc;
- }
+ } else
+ read_unlock(&vmlist_lock);
/* where page 0 not mapped, write zeros into buffer */
#if defined (__i386__) || defined (__mc68000__)
diff -urN -X dontdiff linux/include/linux/vmalloc.h vmalloc/include/linux/vmalloc.h
--- linux/include/linux/vmalloc.h Sat Mar 18 20:11:01 2000
+++ vmalloc/include/linux/vmalloc.h Wed May 3 13:08:55 2000
@@ -3,6 +3,7 @@
#include <linux/sched.h>
#include <linux/mm.h>
+#include <linux/spinlock.h>
#include <asm/pgtable.h>
@@ -24,6 +25,11 @@
void vmfree_area_pages(unsigned long address, unsigned long size);
int vmalloc_area_pages(unsigned long address, unsigned long size);
+/* vmlist_lock is a read-write spinlock that protects vmlist
+ * Used in mm/vmalloc.c (get_vm_area() and vfree()) and fs/proc/kcore.c.
+ */
+extern rwlock_t vmlist_lock;
+
extern struct vm_struct * vmlist;
#endif
diff -urN -X dontdiff linux/ipc/util.c vmalloc/ipc/util.c
--- linux/ipc/util.c Wed Mar 8 17:16:24 2000
+++ vmalloc/ipc/util.c Wed May 3 12:54:19 2000
@@ -159,25 +159,19 @@
void* ipc_alloc(int size)
{
void* out;
- if(size > PAGE_SIZE) {
- lock_kernel();
+ if(size > PAGE_SIZE)
out = vmalloc(size);
- unlock_kernel();
- } else {
+ else
out = kmalloc(size, GFP_KERNEL);
- }
return out;
}
void ipc_free(void* ptr, int size)
{
- if(size > PAGE_SIZE) {
- lock_kernel();
+ if(size > PAGE_SIZE)
vfree(ptr);
- unlock_kernel();
- } else {
+ else
kfree(ptr);
- }
}
/*
diff -urN -X dontdiff linux/mm/vmalloc.c vmalloc/mm/vmalloc.c
--- linux/mm/vmalloc.c Fri Mar 24 11:01:34 2000
+++ vmalloc/mm/vmalloc.c Wed May 3 13:09:07 2000
@@ -3,14 +3,17 @@
*
* Copyright (C) 1993 Linus Torvalds
* Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
+ * SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
*/
#include <linux/malloc.h>
#include <linux/vmalloc.h>
+#include <linux/spinlock.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
+rwlock_t vmlist_lock = RW_LOCK_UNLOCKED;
struct vm_struct * vmlist = NULL;
static inline void free_area_pte(pmd_t * pmd, unsigned long address, unsigned long size)
@@ -163,11 +166,13 @@
if (!area)
return NULL;
addr = VMALLOC_START;
+ write_lock(&vmlist_lock);
for (p = &vmlist; (tmp = *p) ; p = &tmp->next) {
if (size + addr < (unsigned long) tmp->addr)
break;
addr = tmp->size + (unsigned long) tmp->addr;
if (addr > VMALLOC_END-size) {
+ write_unlock(&vmlist_lock);
kfree(area);
return NULL;
}
@@ -177,6 +182,7 @@
area->size = size + PAGE_SIZE;
area->next = *p;
*p = area;
+ write_unlock(&vmlist_lock);
return area;
}
@@ -190,14 +196,17 @@
printk(KERN_ERR "Trying to vfree() bad address (%p)\n", addr);
return;
}
+ write_lock(&vmlist_lock);
for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
if (tmp->addr == addr) {
*p = tmp->next;
vmfree_area_pages(VMALLOC_VMADDR(tmp->addr), tmp->size);
kfree(tmp);
+ write_unlock(&vmlist_lock);
return;
}
}
+ write_unlock(&vmlist_lock);
printk(KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n", addr);
}
@@ -235,6 +244,7 @@
if ((unsigned long) addr + count < count)
count = -(unsigned long) addr;
+ read_lock(&vmlist_lock);
for (tmp = vmlist; tmp; tmp = tmp->next) {
vaddr = (char *) tmp->addr;
if (addr >= vaddr + tmp->size - PAGE_SIZE)
@@ -242,7 +252,7 @@
while (addr < vaddr) {
if (count == 0)
goto finished;
- put_user('\0', buf);
+ *buf = '\0';
buf++;
addr++;
count--;
@@ -251,12 +261,13 @@
do {
if (count == 0)
goto finished;
- put_user(*addr, buf);
+ *buf = *addr;
buf++;
addr++;
count--;
} while (--n > 0);
}
finished:
+ read_unlock(&vmlist_lock);
return buf - buf_start;
}
-
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