efi: capsule: use atomic kmap for transient sglist mappings

Don't use the heavy-weight kmap() API to create short-lived mappings
of the scatter-gather list entries that are released as soon as the
entries are written. Instead, use kmap_atomic(), which is more suited
to this purpose.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

diff --git a/drivers/firmware/efi/capsule.c b/drivers/firmware/efi/capsule.c
index 598b7800d14eca4c0c8906cda67d1f4ae6f29253..43f6fe7bfe80fb91506d3e86928f486852aed477 100644 (file)
--- a/drivers/firmware/efi/capsule.c
+++ b/drivers/firmware/efi/capsule.c
@@ -244,7 +244,7 @@ int efi_capsule_update(efi_capsule_header_t *capsule, phys_addr_t *pages)
        for (i = 0; i < sg_count; i++) {
                efi_capsule_block_desc_t *sglist;
 
-               sglist = kmap(sg_pages[i]);
+               sglist = kmap_atomic(sg_pages[i]);
 
                for (j = 0; j < SGLIST_PER_PAGE && count > 0; j++) {
                        u64 sz = min_t(u64, imagesize,
@@ -265,7 +265,7 @@ int efi_capsule_update(efi_capsule_header_t *capsule, phys_addr_t *pages)
                else
                        sglist[j].data = page_to_phys(sg_pages[i + 1]);
 
-               kunmap(sg_pages[i]);
+               kunmap_atomic(sglist);
        }
 
        mutex_lock(&capsule_mutex);