ACPI, APEI, Fix error path for memory allocation

In ERST debug/test support patch, a dynamic allocated buffer is
used. The may-failed memory allocation should be tried firstly before
free the previous buffer.

APEI resource management memory allocation related error path is fixed
too.

v2:

- Fix error messages for APEI resources management

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 10 insertions, 6 deletions

diff --git a/drivers/acpi/apei/erst-dbg.c b/drivers/acpi/apei/erst-dbg.c
index 5281ddda277..8561cfefa3d 100644
--- a/drivers/acpi/apei/erst-dbg.c
+++ b/drivers/acpi/apei/erst-dbg.c
@@ -111,11 +111,13 @@ retry:
 		goto out;
 	}
 	if (len > erst_dbg_buf_len) {
-		kfree(erst_dbg_buf);
+		void *p;
 		rc = -ENOMEM;
-		erst_dbg_buf = kmalloc(len, GFP_KERNEL);
-		if (!erst_dbg_buf)
+		p = kmalloc(len, GFP_KERNEL);
+		if (!p)
 			goto out;
+		kfree(erst_dbg_buf);
+		erst_dbg_buf = p;
 		erst_dbg_buf_len = len;
 		goto retry;
 	}
@@ -150,11 +152,13 @@ static ssize_t erst_dbg_write(struct file *filp, const char __user *ubuf,
 	if (mutex_lock_interruptible(&erst_dbg_mutex))
 		return -EINTR;
 	if (usize > erst_dbg_buf_len) {
-		kfree(erst_dbg_buf);
+		void *p;
 		rc = -ENOMEM;
-		erst_dbg_buf = kmalloc(usize, GFP_KERNEL);
-		if (!erst_dbg_buf)
+		p = kmalloc(usize, GFP_KERNEL);
+		if (!p)
 			goto out;
+		kfree(erst_dbg_buf);
+		erst_dbg_buf = p;
 		erst_dbg_buf_len = usize;
 	}
 	rc = copy_from_user(erst_dbg_buf, ubuf, usize);