On Monday, January 17, 2011 12:55:26 pm Sergey Kandaurov wrote:
> Hi,
> 
> I see this "malloc with non-sleepable" on current during boot.
> It's strange that I don't see it if I boot via pxe/nfs.
> 
> if_alloc() calls ifindex_alloc_locked() under IFNET_WLOCK() which
> might call if_grow().
> Looks like a regression from r196553.

I'm guessing that ifindex_alloc() should drop the lock and retry the 
allocation after calling if_grow()?  This compiles, but I haven't booted it 
yet:

Index: if.c
===================================================================
--- if.c        (revision 217400)
+++ if.c        (working copy)
@@ -266,6 +266,7 @@ ifindex_alloc_locked(u_short *idxp)
 
        IFNET_WLOCK_ASSERT();
 
+retry:
        /*
         * Try to find an empty slot below V_if_index.  If we fail, take the
         * next slot.
@@ -278,10 +279,11 @@ ifindex_alloc_locked(u_short *idxp)
        /* Catch if_index overflow. */
        if (idx < 1)
                return (ENOSPC);
-       if (idx > V_if_index)
-               V_if_index = idx;
-       if (V_if_index >= V_if_indexlim)
+       if (idx > V_if_index) {
                if_grow();
+               goto retry;
+       }
+       V_if_index = idx;
        *idxp = idx;
        return (0);
 }
@@ -385,16 +387,25 @@ VNET_SYSUNINIT(vnet_if_uninit, SI_SUB_INIT_IF, SI_
 static void
 if_grow(void)
 {
+       int oldlim;
        u_int n;
        struct ifindex_entry *e;
 
-       V_if_indexlim <<= 1;
-       n = V_if_indexlim * sizeof(*e);
+       IFNET_WLOCK_ASSERT();
+       oldlim = V_if_indexlim;
+       IFNET_WUNLOCK();
+       n = (oldlim << 1) * sizeof(*e);
        e = malloc(n, M_IFNET, M_WAITOK | M_ZERO);
+       IFNET_WLOCK();
+       if (V_if_indexlim != oldlim) {
+               free(e, M_IFNET);
+               return;
+       }
        if (V_ifindex_table != NULL) {
                memcpy((caddr_t)e, (caddr_t)V_ifindex_table, n/2);
                free((caddr_t)V_ifindex_table, M_IFNET);
        }
+       V_if_indexlim <<= 1;
        V_ifindex_table = e;
 }
 

-- 
John Baldwin
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