[Xen-devel] [PATCH v2] xen/grant-table: remove multiple BUG_ON on gnttab_interface

[Aditya Pakki]

gnttab_request_version() always sets the gnttab_interface variable
and the assertions to check for empty gnttab_interface is unnecessary.
The patch eliminates multiple such assertions.

Signed-off-by: Aditya Pakki 
---
v1: Eliminate more BUG_ON calls, as suggested by Juergen Gross.
---
 drivers/xen/grant-table.c | 4 
 1 file changed, 4 deletions(-)

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 49b381e104ef..7b36b51cdb9f 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -664,7 +664,6 @@ static int grow_gnttab_list(unsigned int more_frames)
unsigned int nr_glist_frames, new_nr_glist_frames;
unsigned int grefs_per_frame;
 
-   BUG_ON(gnttab_interface == NULL);
grefs_per_frame = gnttab_interface->grefs_per_grant_frame;
 
new_nr_grant_frames = nr_grant_frames + more_frames;
@@ -1160,7 +1159,6 @@ EXPORT_SYMBOL_GPL(gnttab_unmap_refs_sync);
 
 static unsigned int nr_status_frames(unsigned int nr_grant_frames)
 {
-   BUG_ON(gnttab_interface == NULL);
return gnttab_frames(nr_grant_frames, SPP);
 }
 
@@ -1388,7 +1386,6 @@ static int gnttab_expand(unsigned int req_entries)
int rc;
unsigned int cur, extra;
 
-   BUG_ON(gnttab_interface == NULL);
cur = nr_grant_frames;
extra = ((req_entries + gnttab_interface->grefs_per_grant_frame - 1) /
 gnttab_interface->grefs_per_grant_frame);
@@ -1423,7 +1420,6 @@ int gnttab_init(void)
/* Determine the maximum number of frames required for the
 * grant reference free list on the current hypervisor.
 */
-   BUG_ON(gnttab_interface == NULL);
max_nr_glist_frames = (max_nr_grant_frames *
   gnttab_interface->grefs_per_grant_frame / RPP);
 
-- 
2.20.1


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[Xen-devel] [PATCH] xen/grant-table: remove unnecessary BUG_ON on gnttab_interface

[Aditya Pakki]

grow_gnttab_list() checks for NULL on gnttab_interface immediately
after gnttab_expand() check. The patch removes the redundant assertion
and replaces the BUG_ON call with recovery code.

Signed-off-by: Aditya Pakki 
---
 drivers/xen/grant-table.c | 9 ++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 49b381e104ef..f59694c352be 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -664,7 +664,6 @@ static int grow_gnttab_list(unsigned int more_frames)
unsigned int nr_glist_frames, new_nr_glist_frames;
unsigned int grefs_per_frame;
 
-   BUG_ON(gnttab_interface == NULL);
grefs_per_frame = gnttab_interface->grefs_per_grant_frame;
 
new_nr_grant_frames = nr_grant_frames + more_frames;
@@ -1388,7 +1387,9 @@ static int gnttab_expand(unsigned int req_entries)
int rc;
unsigned int cur, extra;
 
-   BUG_ON(gnttab_interface == NULL);
+   if (!gnttab_interface)
+   return -EINVAL;
+
cur = nr_grant_frames;
extra = ((req_entries + gnttab_interface->grefs_per_grant_frame - 1) /
 gnttab_interface->grefs_per_grant_frame);
@@ -1423,7 +1424,9 @@ int gnttab_init(void)
/* Determine the maximum number of frames required for the
 * grant reference free list on the current hypervisor.
 */
-   BUG_ON(gnttab_interface == NULL);
+   if (!gnttab_interface)
+   return -EINVAL;
+
max_nr_glist_frames = (max_nr_grant_frames *
   gnttab_interface->grefs_per_grant_frame / RPP);
 
-- 
2.20.1


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