This is an example of how to add a context set/unset wrapper inside
the kernel, for something like open flags:
1) Alloc a new SYSIND_CTX_* sequential index inside linux/indirect.h
2) Define a new "struct sysind_ctx_*" to be used by userspace
3) Define proper set/unset functions inside kernel/sys_indirect.c
Signed-off-by: Davide Libenzi <[email protected]>
- Davide
---
include/linux/indirect.h | 7 +++++++
kernel/sys_indirect.c | 32 +++++++++++++++++++++++++++++++-
2 files changed, 38 insertions(+), 1 deletion(-)
Index: linux-2.6.mod/include/linux/indirect.h
===================================================================
--- linux-2.6.mod.orig/include/linux/indirect.h 2007-06-29 12:58:11.000000000 -0700
+++ linux-2.6.mod/include/linux/indirect.h 2007-06-29 12:58:11.000000000 -0700
@@ -8,10 +8,17 @@
#ifndef _LINUX_INDIRECT_H
#define _LINUX_INDIRECT_H
+#define SYSIND_CTX_OPENFLAGS 0
+
struct indirect_ctx {
__u32 ctx;
};
+struct sysind_ctx_OPENFLAGS {
+ __u32 ctx;
+ __u32 flags;
+};
+
#ifdef __KERNEL__
#include <linux/fsalloc.h>
Index: linux-2.6.mod/kernel/sys_indirect.c
===================================================================
--- linux-2.6.mod.orig/kernel/sys_indirect.c 2007-06-29 12:58:11.000000000 -0700
+++ linux-2.6.mod/kernel/sys_indirect.c 2007-06-29 12:58:11.000000000 -0700
@@ -24,9 +24,39 @@
void (*unset)(struct indirect_op *);
};
+struct indirect_op_OPENFLAGS {
+ struct indirect_op op;
+ unsigned long flags;
+};
+
+static int set_OPENFLAGS(struct fsa_context *ator,
+ const struct indirect_ctx __user *uctx,
+ struct indirect_op **pnew)
+{
+ struct indirect_op_OPENFLAGS *iop;
+ struct sysind_ctx_OPENFLAGS kctx;
+
+ if (copy_from_user(&kctx, uctx, sizeof(*uctx)))
+ return -EFAULT;
+ iop = fsa_alloc(ator, sizeof(struct indirect_op_OPENFLAGS));
+ if (unlikely(!iop))
+ return -ENOMEM;
+ iop->op.ctx = kctx.ctx;
+ /* iop->flags = current->def_open_flags; */
+ /* current->def_open_flags = kctx.flags; */
+ *pnew = (struct indirect_op *) iop;
+
+ return 0;
+}
+
+static void unset_OPENFLAGS(struct indirect_op *iop)
+{
+ /* current->def_open_flags = ((struct indirect_op_OPENFLAGS *) iop)->flags; */
+}
+
static const struct indirect_procs inprocs[] =
{
- { NULL, NULL },
+ [SYSIND_CTX_OPENFLAGS] = { set_OPENFLAGS, unset_OPENFLAGS },
};
/**
-
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