From eb3b3c93afc4a4244590f7d1e715e8b6749585a9 Mon Sep 17 00:00:00 2001 From: "Fabio M. De Francesco" Date: Thu, 1 Sep 2022 17:44:08 +0200 Subject: [PATCH] misc/xilinx_sdfec: Replace kmap() with kmap_local_page() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit kmap() is being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as the mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap’s pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and still valid. Since its use in xilinx_sdfec.c is safe, replace kmap()i / kunmap() with kmap_local_page() / kunmap_local(). Cc: "Venkataramanan, Anirudh" Suggested-by: Ira Weiny Signed-off-by: Fabio M. De Francesco Link: https://lore.kernel.org/r/20220901154408.23984-3-fmdefrancesco@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/misc/xilinx_sdfec.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/misc/xilinx_sdfec.c b/drivers/misc/xilinx_sdfec.c index 4b1d82a..cb9506f 100644 --- a/drivers/misc/xilinx_sdfec.c +++ b/drivers/misc/xilinx_sdfec.c @@ -636,7 +636,7 @@ static int xsdfec_table_write(struct xsdfec_dev *xsdfec, u32 offset, } for (i = 0; i < nr_pages; i++) { - addr = kmap(pages[i]); + addr = kmap_local_page(pages[i]); do { xsdfec_regwrite(xsdfec, base_addr + ((offset + reg) * @@ -645,7 +645,7 @@ static int xsdfec_table_write(struct xsdfec_dev *xsdfec, u32 offset, reg++; } while ((reg < len) && ((reg * XSDFEC_REG_WIDTH_JUMP) % PAGE_SIZE)); - kunmap(pages[i]); + kunmap_local(addr); unpin_user_page(pages[i]); } return 0; -- 2.7.4