[PATCH net-next 09/15] nfp: fix invalid area detection

[Jakub Kicinski]

Core should detect when someone is trying to request an access
window which is too large for a given type of access.  Otherwise
the requester will be put on a wait queue for ever without any
error message.

Add const qualifiers to clarify that we are only looking at read-
-only members in relevant functions.

Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
---
 .../ethernet/netronome/nfp/nfpcore/nfp6000_pcie.c  | 29 +++++++++++-----------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp6000_pcie.c 
b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp6000_pcie.c
index 15cc3e77cf6a..43dc68e01274 100644
--- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp6000_pcie.c
+++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp6000_pcie.c
@@ -217,7 +217,7 @@ static resource_size_t nfp_bar_resource_start(struct 
nfp_bar *bar)
 #define TARGET_WIDTH_64    8
 
 static int
-compute_bar(struct nfp6000_pcie *nfp, struct nfp_bar *bar,
+compute_bar(const struct nfp6000_pcie *nfp, const struct nfp_bar *bar,
            u32 *bar_config, u64 *bar_base,
            int tgt, int act, int tok, u64 offset, size_t size, int width)
 {
@@ -410,35 +410,36 @@ find_matching_bar(struct nfp6000_pcie *nfp,
 
 /* Return EAGAIN if no resource is available */
 static int
-find_unused_bar_noblock(struct nfp6000_pcie *nfp,
+find_unused_bar_noblock(const struct nfp6000_pcie *nfp,
                        int tgt, int act, int tok,
                        u64 offset, size_t size, int width)
 {
-       int n, invalid = 0;
+       int n, busy = 0;
 
        for (n = 0; n < nfp->bars; n++) {
-               struct nfp_bar *bar = &nfp->bar[n];
+               const struct nfp_bar *bar = &nfp->bar[n];
                int err;
 
-               if (bar->bitsize == 0) {
-                       invalid++;
-                       continue;
-               }
-
-               if (atomic_read(&bar->refcnt) != 0)
+               if (!bar->bitsize)
                        continue;
 
                /* Just check to see if we can make it fit... */
                err = compute_bar(nfp, bar, NULL, NULL,
                                  tgt, act, tok, offset, size, width);
+               if (err)
+                       continue;
 
-               if (err < 0)
-                       invalid++;
-               else
+               if (!atomic_read(&bar->refcnt))
                        return n;
+
+               busy++;
        }
 
-       return (n == invalid) ? -EINVAL : -EAGAIN;
+       if (WARN(!busy, "No suitable BAR found for request tgt:0x%x act:0x%x 
tok:0x%x off:0x%llx size:%zd width:%d\n",
+                tgt, act, tok, offset, size, width))
+               return -EINVAL;
+
+       return -EAGAIN;
 }
 
 static int
-- 
2.11.0