[Xen-devel] [PATCH] linux-2.6.18: streamline clearing of memory in a few places

["Jan Beulich" <JBeulich@xxxxxxxx>]

- use kzalloc() in favor of kmalloc()+memset() in one more spot
- use clear_page() in favor of memset(, 0, PAGE_SIZE) (also use
  copy_page() in favor of memcpy(, , PAGE_SIZE))
- don't redundantly clear memory

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/arch/i386/mm/init-xen.c
+++ b/arch/i386/mm/init-xen.c
@@ -558,7 +558,7 @@ void __init paging_init(void)
         * dummy page. */
        set_fixmap(FIX_SHARED_INFO, xen_start_info->shared_info);
        HYPERVISOR_shared_info = (shared_info_t *)fix_to_virt(FIX_SHARED_INFO);
-       memset(empty_zero_page, 0, sizeof(empty_zero_page));
+       clear_page(empty_zero_page);
 
        /* Setup mapping of lower 1st MB */
        for (i = 0; i < NR_FIX_ISAMAPS; i++)
--- a/arch/x86_64/mm/init-xen.c
+++ b/arch/x86_64/mm/init-xen.c
@@ -218,7 +218,7 @@ static __init void *spp_getpage(void)
        else if (start_pfn < table_end) {
                ptr = __va(start_pfn << PAGE_SHIFT);
                start_pfn++;
-               memset(ptr, 0, PAGE_SIZE);
+               clear_page(ptr);
        } else
                ptr = alloc_bootmem_pages(PAGE_SIZE);
        if (!ptr || ((unsigned long)ptr & ~PAGE_MASK))
@@ -376,7 +376,7 @@ static __meminit void *alloc_static_page
 
        *phys = start_pfn << PAGE_SHIFT;
        start_pfn++;
-       memset((void *)va, 0, PAGE_SIZE);
+       clear_page((void *)va);
        return (void *)va;
 } 
 
@@ -728,7 +728,7 @@ static void xen_finish_init_mapping(void
        /* Switch to the real shared_info page, and clear the dummy page. */
        set_fixmap(FIX_SHARED_INFO, xen_start_info->shared_info);
        HYPERVISOR_shared_info = (shared_info_t *)fix_to_virt(FIX_SHARED_INFO);
-       memset(empty_zero_page, 0, sizeof(empty_zero_page));
+       clear_page(empty_zero_page);
 
        /* Set up mapping of lowest 1MB of physical memory. */
        for (i = 0; i < NR_FIX_ISAMAPS; i++)
--- a/drivers/xen/core/gnttab.c
+++ b/drivers/xen/core/gnttab.c
@@ -543,7 +543,7 @@ int gnttab_copy_grant_page(grant_ref_t r
 
        new_addr = page_address(new_page);
        addr = page_address(page);
-       memcpy(new_addr, addr, PAGE_SIZE);
+       copy_page(new_addr, addr);
 
        pfn = page_to_pfn(page);
        mfn = pfn_to_mfn(pfn);
--- a/drivers/xen/core/machine_reboot.c
+++ b/drivers/xen/core/machine_reboot.c
@@ -89,7 +89,7 @@ static void post_suspend(int suspend_can
                BUG();
        HYPERVISOR_shared_info = (shared_info_t *)fix_to_virt(FIX_SHARED_INFO);
 
-       memset(empty_zero_page, 0, PAGE_SIZE);
+       clear_page(empty_zero_page);
 
        fpp = PAGE_SIZE/sizeof(unsigned long);
        for (i = 0, j = 0, k = -1; i < max_pfn; i += fpp, j++) {
--- a/drivers/xen/core/smpboot.c
+++ b/drivers/xen/core/smpboot.c
@@ -198,17 +198,12 @@ static void __cpuinit cpu_initialize_con
        ctxt.flags = VGCF_IN_KERNEL;
        ctxt.user_regs.ds = __USER_DS;
        ctxt.user_regs.es = __USER_DS;
-       ctxt.user_regs.fs = 0;
-       ctxt.user_regs.gs = 0;
        ctxt.user_regs.ss = __KERNEL_DS;
        ctxt.user_regs.eip = (unsigned long)cpu_bringup_and_idle;
        ctxt.user_regs.eflags = X86_EFLAGS_IF | 0x1000; /* IOPL_RING1 */
 
-       memset(&ctxt.fpu_ctxt, 0, sizeof(ctxt.fpu_ctxt));
-
        smp_trap_init(ctxt.trap_ctxt);
 
-       ctxt.ldt_ents = 0;
 
        ctxt.gdt_frames[0] = virt_to_mfn(gdt_descr->address);
        ctxt.gdt_ents      = gdt_descr->size / 8;
--- a/drivers/xen/netback/interface.c
+++ b/drivers/xen/netback/interface.c
@@ -236,7 +236,6 @@ netif_t *netif_alloc(struct device *pare
        SET_NETDEV_DEV(dev, parent);
 
        netif = netdev_priv(dev);
-       memset(netif, 0, sizeof(*netif));
        netif->domid  = domid;
        netif->handle = handle;
        netif->can_sg = 1;
--- a/drivers/xen/sfc_netutil/accel_cuckoo_hash.c
+++ b/drivers/xen/sfc_netutil/accel_cuckoo_hash.c
@@ -76,7 +76,7 @@ int cuckoo_hash_init(cuckoo_hash_table *
        BUG_ON(length_bits >= sizeof(unsigned) * 8);
        BUG_ON(key_length > sizeof(cuckoo_hash_key));
 
-       table_mem = kmalloc(sizeof(cuckoo_hash_entry) * 2 * length, GFP_KERNEL);
+       table_mem = kzalloc(sizeof(cuckoo_hash_entry) * 2 * length, GFP_KERNEL);
 
        if (table_mem == NULL)
                return -ENOMEM;
@@ -92,9 +92,6 @@ int cuckoo_hash_init(cuckoo_hash_table *
 
        set_hash_parameters(hashtab);
 
-       /* Zero the table */
-       memset(hashtab->table0, 0, length * 2 * sizeof(cuckoo_hash_entry));
-
        return 0;
 }
 EXPORT_SYMBOL_GPL(cuckoo_hash_init);
--- a/drivers/xen/tpmback/interface.c
+++ b/drivers/xen/tpmback/interface.c
@@ -93,7 +93,7 @@ int tpmif_map(tpmif_t *tpmif, grant_ref_
        tpmif->tx_area = area;
 
        tpmif->tx = (tpmif_tx_interface_t *)area->addr;
-       memset(tpmif->tx, 0, PAGE_SIZE);
+       clear_page(tpmif->tx);
 
        err = bind_interdomain_evtchn_to_irqhandler(
                tpmif->domid, evtchn, tpmif_be_int, 0, tpmif->devname, tpmif);



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