PCI: endpoint: Fix for concurrent memory allocation in OB address region

commit 04e046ca57ebed3943422dee10eec9e73aec081e upstream.

pci-epc-mem uses a bitmap to manage the Endpoint outbound (OB) address
region. This address region will be shared by multiple endpoint
functions (in the case of multi function endpoint) and it has to be
protected from concurrent access to avoid updating an inconsistent state.

Use a mutex to protect bitmap updates to prevent the memory
allocation API from returning incorrect addresses.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/pci/endpoint/pci-epc-mem.c b/drivers/pci/endpoint/pci-epc-mem.c
index d2b174ce15decd8e9a58c3cd7fc9752fd7052853..abfac1109a13eb2f03bc80bf7a3389f24637bf0e 100644 (file)
--- a/drivers/pci/endpoint/pci-epc-mem.c
+++ b/drivers/pci/endpoint/pci-epc-mem.c
@@ -79,6 +79,7 @@ int __pci_epc_mem_init(struct pci_epc *epc, phys_addr_t phys_base, size_t size,
        mem->page_size = page_size;
        mem->pages = pages;
        mem->size = size;
+       mutex_init(&mem->lock);
 
        epc->mem = mem;
 
@@ -122,7 +123,7 @@ void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
                                     phys_addr_t *phys_addr, size_t size)
 {
        int pageno;
-       void __iomem *virt_addr;
+       void __iomem *virt_addr = NULL;
        struct pci_epc_mem *mem = epc->mem;
        unsigned int page_shift = ilog2(mem->page_size);
        int order;
@@ -130,15 +131,18 @@ void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
        size = ALIGN(size, mem->page_size);
        order = pci_epc_mem_get_order(mem, size);
 
+       mutex_lock(&mem->lock);
        pageno = bitmap_find_free_region(mem->bitmap, mem->pages, order);
        if (pageno < 0)
-               return NULL;
+               goto ret;
 
        *phys_addr = mem->phys_base + ((phys_addr_t)pageno << page_shift);
        virt_addr = ioremap(*phys_addr, size);
        if (!virt_addr)
                bitmap_release_region(mem->bitmap, pageno, order);
 
+ret:
+       mutex_unlock(&mem->lock);
        return virt_addr;
 }
 EXPORT_SYMBOL_GPL(pci_epc_mem_alloc_addr);
@@ -164,7 +168,9 @@ void pci_epc_mem_free_addr(struct pci_epc *epc, phys_addr_t phys_addr,
        pageno = (phys_addr - mem->phys_base) >> page_shift;
        size = ALIGN(size, mem->page_size);
        order = pci_epc_mem_get_order(mem, size);
+       mutex_lock(&mem->lock);
        bitmap_release_region(mem->bitmap, pageno, order);
+       mutex_unlock(&mem->lock);
 }
 EXPORT_SYMBOL_GPL(pci_epc_mem_free_addr);
 

diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index 56f1846b9d396cf90ee6ad1950f9ba615b4e87a6..c8e39607dbb734d34a94cdf4b743b9e22180f00e 100644 (file)
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -71,6 +71,7 @@ struct pci_epc_ops {
  * @bitmap: bitmap to manage the PCI address space
  * @pages: number of bits representing the address region
  * @page_size: size of each page
+ * @lock: mutex to protect bitmap
  */
 struct pci_epc_mem {
        phys_addr_t     phys_base;
@@ -78,6 +79,8 @@ struct pci_epc_mem {
        unsigned long   *bitmap;
        size_t          page_size;
        int             pages;
+       /* mutex to protect against concurrent access for memory allocation*/
+       struct mutex    lock;
 };
 
 /**