The following wrong commit triggers issues in acpi_get_table_with_size()
users:
Subject: ACPICA: Tables: Back port acpi_get_table_with_size() and
early_acpi_os_unmap_memory() from Linux kernel
The function is invented to be a replacement of acpi_get_table() during
early stage so that the early mapped pointer will not be stored in ACPICA
core and thus the late stage acpi_get_table() won't return a wrong pointer.
However the mapping size is returned just because it is required by
early_acpi_os_unmap_memory() to unmap the pointer during early stage.
As the mapping size equals to the acpi_table_header.length
(see acpi_tb_init_table_descriptor() and acpi_tb_validate_table()), when
such a convenient result is returned, driver code will start to use it
instead of accessing acpi_table_header to obtain the length.
So the commit can trigger problems in such drivers as it returns 0 now. And
it did bring a trouble to drivers/acpi/nfit/core.c. So before cleaning up
the drivers, we should keep the old semantics of the API.
This patch fixes the wrong commit by returning the acpi_table_header.length
from acpi_get_table_with_size().
Reported-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
---
drivers/acpi/osl.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 5bef0f65..d0b273f 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -445,8 +445,16 @@ void __ref acpi_os_unmap_memory(void *virt, acpi_size size)
status = acpi_get_table(signature, instance, out_table);
if (ACPI_SUCCESS(status)) {
- /* No longer used by early_acpi_os_unmap_memory() */
- *tbl_size = 0;
+ /*
+ * "tbl_size" is no longer used by
+ * early_acpi_os_unmap_memory(), but is still used by the
+ * ACPI table drivers. So sets it to the length of the
+ * table when the tbl_size is requested.
+ * "out_table" is not sanity checked as AE_BAD_PARAMETER
+ * is returned if it is NULL.
+ */
+ if (tbl_size && *out_table)
+ *tbl_size = (*out_table)->length;
}
return (status);
--
1.7.10
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