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SubjectRe: [PATCH]updated ipc lock patch
Date
> diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal working-2.5.44-mm4-ipc-rcu/include/linux/msg.h working-2.5.44-mm4-ipc-rcu-fix/include/linux/msg.h
> --- working-2.5.44-mm4-ipc-rcu/include/linux/msg.h 2002-07-21 17:43:10.000000000 +1000
> +++ working-2.5.44-mm4-ipc-rcu-fix/include/linux/msg.h 2002-10-28 11:12:54.000000000 +1100

Oops. That patch had some fluff in msg.h and sem.h. Delete those, or
just use this instead (still against Mingming's mm4 "ignore kmalloc
failure" patch):

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal working-2.5.44-mm4-ipc-rcu/ipc/util.c working-2.5.44-mm4-ipc-rcu-fix/ipc/util.c
--- working-2.5.44-mm4-ipc-rcu/ipc/util.c 2002-10-28 11:08:35.000000000 +1100
+++ working-2.5.44-mm4-ipc-rcu-fix/ipc/util.c 2002-10-28 12:01:09.000000000 +1100
@@ -213,21 +213,49 @@ struct kern_ipc_perm* ipc_rmid(struct ip
return p;
}

+struct ipc_rcu_kmalloc
+{
+ struct rcu_head rcu;
+ /* "void *" makes sure alignment of following data is sane. */
+ void *data[0];
+};
+
+struct ipc_rcu_vmalloc
+{
+ struct rcu_head rcu;
+ struct work_struct work;
+ /* "void *" makes sure alignment of following data is sane. */
+ void *data[0];
+};
+
+static inline int use_vmalloc(int size)
+{
+ /* Too big for a single page? */
+ if (sizeof(struct ipc_rcu_kmalloc) + size > PAGE_SIZE)
+ return 1;
+ return 0;
+}
+
/**
* ipc_alloc - allocate ipc space
* @size: size desired
*
* Allocate memory from the appropriate pools and return a pointer to it.
- * NULL is returned if the allocation fails
+ * NULL is returned if the allocation fails. This can be freed with
+ * ipc_free (to free immediately) or ipc_rcu_free (to free once safe).
*/
-
void* ipc_alloc(int size)
{
void* out;
- if(size > PAGE_SIZE)
- out = vmalloc(size);
- else
- out = kmalloc(size, GFP_KERNEL);
+ /* We prepend the allocation with the rcu struct, and
+ workqueue if necessary (for vmalloc). */
+ if (use_vmalloc(size)) {
+ out = vmalloc(sizeof(struct ipc_rcu_vmalloc) + size);
+ if (out) out += sizeof(struct ipc_rcu_vmalloc);
+ } else {
+ out = kmalloc(sizeof(struct ipc_rcu_kmalloc)+size, GFP_KERNEL);
+ if (out) out += sizeof(struct ipc_rcu_kmalloc);
+ }
return out;
}

@@ -242,48 +270,36 @@ void* ipc_alloc(int size)

void ipc_free(void* ptr, int size)
{
- if(size > PAGE_SIZE)
- vfree(ptr);
+ if (use_vmalloc(size))
+ vfree(ptr - sizeof(struct ipc_rcu_vmalloc));
else
- kfree(ptr);
+ kfree(ptr - sizeof(struct ipc_rcu_kmalloc));
}

/*
* Since RCU callback function is called in bh,
* we need to defer the vfree to schedule_work
*/
-static void ipc_free_scheduled(void* arg)
+static void ipc_schedule_free(void *arg)
{
- struct rcu_ipc_free *a = (struct rcu_ipc_free *)arg;
- vfree(a->ptr);
- kfree(a);
-}
+ struct ipc_rcu_vmalloc *free = arg;

-static void ipc_free_callback(void* arg)
-{
- struct rcu_ipc_free *a = (struct rcu_ipc_free *)arg;
- /*
- * if data is vmalloced, then we need to delay the free
- */
- if (a->size > PAGE_SIZE) {
- INIT_WORK(&a->work, ipc_free_scheduled, arg);
- schedule_work(&a->work);
- } else {
- kfree(a->ptr);
- kfree(a);
- }
+ INIT_WORK(&free->work, vfree, free);
+ schedule_work(&free->work);
}

void ipc_rcu_free(void* ptr, int size)
{
- struct rcu_ipc_free* arg;
-
- arg = (struct rcu_ipc_free *) kmalloc(sizeof(*arg), GFP_KERNEL);
- if (arg == NULL)
- return;
- arg->ptr = ptr;
- arg->size = size;
- call_rcu(&arg->rcu_head, ipc_free_callback, arg);
+ if (use_vmalloc(size)) {
+ struct ipc_rcu_vmalloc *free;
+ free = ptr - sizeof(*free);
+ call_rcu(&free->rcu, ipc_schedule_free, free);
+ } else {
+ struct ipc_rcu_kmalloc *free;
+ free = ptr - sizeof(*free);
+ /* kfree takes a "const void *" so gcc warns. So we cast. */
+ call_rcu(&free->rcu, (void (*)(void *))kfree, free);
+ }
}

/**
--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
-
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