nvme-pci: fix host memory buffer allocation fallback

nvme_alloc_host_mem currently contains two loops that are interwinded,
and the outer retry loop turns out to be broken.  Fix this by untangling
the two.

Based on a report an initial patch from Akinobu Mita.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Akinobu Mita <akinobu.mita@gmail.com>
Tested-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 6ba955c..82e23c8 100644 (file)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1612,18 +1612,16 @@ static void nvme_free_host_mem(struct nvme_dev *dev)
        dev->host_mem_descs = NULL;
 }
 
-static int nvme_alloc_host_mem(struct nvme_dev *dev, u64 min, u64 preferred)
+static int __nvme_alloc_host_mem(struct nvme_dev *dev, u64 preferred,
+               u32 chunk_size)
 {
        struct nvme_host_mem_buf_desc *descs;
-       u32 chunk_size, max_entries, len;
+       u32 max_entries, len;
        dma_addr_t descs_dma;
        int i = 0;
        void **bufs;
        u64 size = 0, tmp;
 
-       /* start big and work our way down */
-       chunk_size = min(preferred, (u64)PAGE_SIZE << MAX_ORDER);
-retry:
        tmp = (preferred + chunk_size - 1);
        do_div(tmp, chunk_size);
        max_entries = tmp;
@@ -1650,15 +1648,9 @@ retry:
                i++;
        }
 
-       if (!size || (min && size < min)) {
-               dev_warn(dev->ctrl.device,
-                       "failed to allocate host memory buffer.\n");
+       if (!size)
                goto out_free_bufs;
-       }
 
-       dev_info(dev->ctrl.device,
-               "allocated %lld MiB host memory buffer.\n",
-               size >> ilog2(SZ_1M));
        dev->nr_host_mem_descs = i;
        dev->host_mem_size = size;
        dev->host_mem_descs = descs;
@@ -1679,15 +1671,28 @@ out_free_descs:
        dma_free_coherent(dev->dev, max_entries * sizeof(*descs), descs,
                        descs_dma);
 out:
-       /* try a smaller chunk size if we failed early */
-       if (chunk_size >= PAGE_SIZE * 2 && (i == 0 || size < min)) {
-               chunk_size /= 2;
-               goto retry;
-       }
        dev->host_mem_descs = NULL;
        return -ENOMEM;
 }
 
+static int nvme_alloc_host_mem(struct nvme_dev *dev, u64 min, u64 preferred)
+{
+       u32 chunk_size;
+
+       /* start big and work our way down */
+       for (chunk_size = min_t(u64, preferred, PAGE_SIZE << MAX_ORDER);
+            chunk_size >= PAGE_SIZE * 2;
+            chunk_size /= 2) {
+               if (!__nvme_alloc_host_mem(dev, preferred, chunk_size)) {
+                       if (!min || dev->host_mem_size >= min)
+                               return 0;
+                       nvme_free_host_mem(dev);
+               }
+       }
+
+       return -ENOMEM;
+}
+
 static void nvme_setup_host_mem(struct nvme_dev *dev)
 {
        u64 max = (u64)max_host_mem_size_mb * SZ_1M;
@@ -1715,8 +1720,15 @@ static void nvme_setup_host_mem(struct nvme_dev *dev)
        }
 
        if (!dev->host_mem_descs) {
-               if (nvme_alloc_host_mem(dev, min, preferred))
+               if (nvme_alloc_host_mem(dev, min, preferred)) {
+                       dev_warn(dev->ctrl.device,
+                               "failed to allocate host memory buffer.\n");
                        return;
+               }
+
+               dev_info(dev->ctrl.device,
+                       "allocated %lld MiB host memory buffer.\n",
+                       dev->host_mem_size >> ilog2(SZ_1M));
        }
 
        if (nvme_set_host_mem(dev, enable_bits))