X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=lib%2Fringbuffer%2Fbackend.h;h=ed913325e2ddb70070392226cc9b27b39df18fad;hb=7801e9f45613e82205af194218f1910c4640855f;hp=541dc531ca76765e990635edc1c2a526e2ccdddb;hpb=4ea00e4f764eb18686121161a98e4ef442fed2c0;p=lttng-modules.git

diff --git a/lib/ringbuffer/backend.h b/lib/ringbuffer/backend.h
index 541dc531..ed913325 100644
--- a/lib/ringbuffer/backend.h
+++ b/lib/ringbuffer/backend.h
@@ -1,14 +1,26 @@
-#ifndef _LINUX_RING_BUFFER_BACKEND_H
-#define _LINUX_RING_BUFFER_BACKEND_H
+#ifndef _LIB_RING_BUFFER_BACKEND_H
+#define _LIB_RING_BUFFER_BACKEND_H
 
 /*
- * linux/ringbuffer/backend.h
- *
- * Copyright (C) 2008-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * lib/ringbuffer/backend.h
  *
  * Ring buffer backend (API).
  *
- * Dual LGPL v2.1/GPL v2 license.
+ * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  *
  * Credits to Steven Rostedt for proposing to use an extra-subbuffer owned by
  * the reader in flight recorder mode.
@@ -22,6 +34,7 @@
 #include <linux/list.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
+#include <linux/uaccess.h>
 
 /* Internal helpers */
 #include "../../wrapper/ringbuffer/backend_internal.h"
@@ -149,7 +162,7 @@ void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config,
 }
 
 /**
- * lib_ring_buffer_copy_from_user - write userspace data to a buffer backend
+ * lib_ring_buffer_copy_from_user_inatomic - write userspace data to a buffer backend
  * @config : ring buffer instance configuration
  * @ctx: ring buffer context. (input arguments only)
  * @src : userspace source pointer to copy from
@@ -158,10 +171,11 @@ void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config,
  * This function copies "len" bytes of data from a userspace pointer to a
  * buffer backend, at the current context offset. This is more or less a buffer
  * backend-specific memcpy() operation. Calls the slow path
- * (_ring_buffer_write_from_user) if copy is crossing a page boundary.
+ * (_ring_buffer_write_from_user_inatomic) if copy is crossing a page boundary.
+ * Disable the page fault handler to ensure we never try to take the mmap_sem.
  */
 static inline
-void lib_ring_buffer_copy_from_user(const struct lib_ring_buffer_config *config,
+void lib_ring_buffer_copy_from_user_inatomic(const struct lib_ring_buffer_config *config,
 				    struct lib_ring_buffer_ctx *ctx,
 				    const void __user *src, size_t len)
 {
@@ -173,6 +187,7 @@ void lib_ring_buffer_copy_from_user(const struct lib_ring_buffer_config *config,
 	struct lib_ring_buffer_backend_pages *rpages;
 	unsigned long sb_bindex, id;
 	unsigned long ret;
+	mm_segment_t old_fs = get_fs();
 
 	offset &= chanb->buf_size - 1;
 	sbidx = offset >> chanb->subbuf_size_order;
@@ -185,11 +200,13 @@ void lib_ring_buffer_copy_from_user(const struct lib_ring_buffer_config *config,
 		     config->mode == RING_BUFFER_OVERWRITE
 		     && subbuffer_id_is_noref(config, id));
 
+	set_fs(KERNEL_DS);
+	pagefault_disable();
 	if (unlikely(!access_ok(VERIFY_READ, src, len)))
 		goto fill_buffer;
 
 	if (likely(pagecpy == len)) {
-		ret = lib_ring_buffer_do_copy_from_user(
+		ret = lib_ring_buffer_do_copy_from_user_inatomic(
 			rpages->p[index].virt + (offset & ~PAGE_MASK),
 			src, len);
 		if (unlikely(ret > 0)) {
@@ -198,13 +215,17 @@ void lib_ring_buffer_copy_from_user(const struct lib_ring_buffer_config *config,
 			goto fill_buffer;
 		}
 	} else {
-		_lib_ring_buffer_copy_from_user(bufb, offset, src, len, 0);
+		_lib_ring_buffer_copy_from_user_inatomic(bufb, offset, src, len, 0);
 	}
+	pagefault_enable();
+	set_fs(old_fs);
 	ctx->buf_offset += len;
 
 	return;
 
 fill_buffer:
+	pagefault_enable();
+	set_fs(old_fs);
 	/*
 	 * In the error path we call the slow path version to avoid
 	 * the pollution of static inline code.
@@ -242,9 +263,4 @@ unsigned long lib_ring_buffer_get_records_unread(
 	return records_unread;
 }
 
-ssize_t lib_ring_buffer_file_splice_read(struct file *in, loff_t *ppos,
-					 struct pipe_inode_info *pipe,
-					 size_t len, unsigned int flags);
-loff_t lib_ring_buffer_no_llseek(struct file *file, loff_t offset, int origin);
-
-#endif /* _LINUX_RING_BUFFER_BACKEND_H */
+#endif /* _LIB_RING_BUFFER_BACKEND_H */