[PATCH] rhashtable: avoid -Wrestrict warning on overlapping sprintf output

[Arnd Bergmann]

From: Arnd Bergmann <a...@arndb.de>

sprintf() is declared with a restrict keyword to not allow input and
output to point to the same buffer:

lib/test_rhashtable.c: In function 'print_ht':
lib/test_rhashtable.c:504:4: error: 'sprintf' argument 3 overlaps destination 
object 'buff' [-Werror=restrict]
  504 |    sprintf(buff, "%s\nbucket[%d] -> ", buff, i);
      |    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
lib/test_rhashtable.c:489:7: note: destination object referenced by 
'restrict'-qualified argument 1 was declared here
  489 |  char buff[512] = "";
      |       ^~~~

Rework this function to remember the last offset instead to
avoid the warning.

Signed-off-by: Arnd Bergmann <a...@arndb.de>
---
 lib/test_rhashtable.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c
index 76c607ee6db5..5a1dd4736b56 100644
--- a/lib/test_rhashtable.c
+++ b/lib/test_rhashtable.c
@@ -487,6 +487,7 @@ static unsigned int __init print_ht(struct rhltable *rhlt)
        struct rhashtable *ht;
        const struct bucket_table *tbl;
        char buff[512] = "";
+       int offset = 0;
        unsigned int i, cnt = 0;
 
        ht = &rhlt->ht;
@@ -501,18 +502,18 @@ static unsigned int __init print_ht(struct rhltable *rhlt)
                next = !rht_is_a_nulls(pos) ? rht_dereference(pos->next, ht) : 
NULL;
 
                if (!rht_is_a_nulls(pos)) {
-                       sprintf(buff, "%s\nbucket[%d] -> ", buff, i);
+                       offset += sprintf(buff + offset, "\nbucket[%d] -> ", i);
                }
 
                while (!rht_is_a_nulls(pos)) {
                        struct rhlist_head *list = container_of(pos, struct 
rhlist_head, rhead);
-                       sprintf(buff, "%s[[", buff);
+                       offset += sprintf(buff + offset, "[[");
                        do {
                                pos = &list->rhead;
                                list = rht_dereference(list->next, ht);
                                p = rht_obj(ht, pos);
 
-                               sprintf(buff, "%s val %d (tid=%d)%s", buff, 
p->value.id, p->value.tid,
+                               offset += sprintf(buff + offset, " val %d 
(tid=%d)%s", p->value.id, p->value.tid,
                                        list? ", " : " ");
                                cnt++;
                        } while (list);
@@ -521,7 +522,7 @@ static unsigned int __init print_ht(struct rhltable *rhlt)
                        next = !rht_is_a_nulls(pos) ?
                                rht_dereference(pos->next, ht) : NULL;
 
-                       sprintf(buff, "%s]]%s", buff, !rht_is_a_nulls(pos) ? " 
-> " : "");
+                       offset += sprintf(buff + offset, "]]%s", 
!rht_is_a_nulls(pos) ? " -> " : "");
                }
        }
        printk(KERN_ERR "\n---- ht: ----%s\n-------------\n", buff);
-- 
2.29.2