sched: more robust sd-sysctl entry freeing

It occurred to me this morning that the procname field was dynamically
allocated and needed to be freed.  I started to put in break statements
when allocation failed but it was approaching 50% error handling code.

I came up with this alternative of looping while entry->mode is set and
checking proc_handler instead of ->table.  Alternatively, the string
version of the domain name and cpu number could be stored the structs.

I verified by compiling CONFIG_DEBUG_SLAB and checking the allocation
counts after taking a cpuset exclusive and back.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 11 insertions, 2 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 0da2b2635c54..5e220bf7d4c4 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5272,11 +5272,20 @@ static struct ctl_table *sd_alloc_ctl_entry(int n)
 
 static void sd_free_ctl_entry(struct ctl_table **tablep)
 {
-        struct ctl_table *entry = *tablep;
+        struct ctl_table *entry;
 
-        for (entry = *tablep; entry->procname; entry++)
+        /*
+         * In the intermediate directories, both the child directory and
+         * procname are dynamically allocated and could fail but the mode
+         * will always be set.  In the lowest directory the names are
+         * static strings and all have proc handlers.
+         */
+        for (entry = *tablep; entry->mode; entry++) {
                 if (entry->child)
                         sd_free_ctl_entry(&entry->child);
+                if (entry->proc_handler == NULL)
+                        kfree(entry->procname);
+        }
 
         kfree(*tablep);
         *tablep = NULL;