openwrt_lede/target/linux/mpc85xx/patches-4.4/200-spi-fsl-espi-preallocate-local-buffer.patch

From: Gabor Juhos <juhosg@openwrt.org>
Subject: spi-fsl-espi: avoid frequent high order allocations

The driver allocates 64KiB of memory fro a local buffer before
each transfer and releases that afterwards. When the memory is
fragmented this allocation often fails and causes a warning like
this:

  kworker/u2:2: page allocation failure: order:4, mode:0x10c0d0
  CPU: 0 PID: 7011 Comm: kworker/u2:2 Not tainted 3.10.24 #1
  Workqueue: ffe07000.spi mpc8xxx_spi_work
  Call Trace:
  [c1c6dcf0] [c0006914] show_stack+0x50/0x170 (unreliable)
  [c1c6dd30] [c0259858] dump_stack+0x24/0x34
  [c1c6dd40] [c00672e8] warn_alloc_failed+0x120/0x13c
  [c1c6dd90] [c0069920] __alloc_pages_nodemask+0x574/0x5c8
  [c1c6de20] [c0069990] __get_free_pages+0x1c/0x4c
  [c1c6de30] [c0185174] fsl_espi_do_one_msg+0x128/0x2a0
  [c1c6de90] [c0184290] mpc8xxx_spi_work+0x50/0x7c
  [c1c6dea0] [c0037af8] process_one_work+0x208/0x30c
  [c1c6dec0] [c00387a0] worker_thread+0x20c/0x308
  [c1c6def0] [c003de60] kthread+0xa4/0xa8
  [c1c6df40] [c000c4bc] ret_from_kernel_thread+0x5c/0x64

  m25p80 spi0.0: error -12 reading SR
  end_request: I/O error, dev mtdblock3, sector 680
  SQUASHFS error: squashfs_read_data failed to read block 0x54a4a
  SQUASHFS error: Unable to read data cache entry [54a4a]

Preallocate the buffer from the probe routine to avoid
this.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 drivers/spi/spi-fsl-espi.c | 34 ++++++++++++++++------------------
 drivers/spi/spi-fsl-lib.h  |  1 +
 2 files changed, 17 insertions(+), 18 deletions(-)

--- a/drivers/spi/spi-fsl-espi.c
+++ b/drivers/spi/spi-fsl-espi.c
@@ -332,17 +332,13 @@ static void fsl_espi_do_trans(struct spi
 static void fsl_espi_cmd_trans(struct spi_message *m,
 				struct fsl_espi_transfer *trans, u8 *rx_buff)
 {
+	struct spi_device *spi = m->spi;
+	struct mpc8xxx_spi *mspi = spi_master_get_devdata(spi->master);
 	struct spi_transfer *t;
-	u8 *local_buf;
+	u8 *local_buf = mspi->local_buf;
 	int i = 0;
 	struct fsl_espi_transfer *espi_trans = trans;
 
-	local_buf = kzalloc(SPCOM_TRANLEN_MAX, GFP_KERNEL);
-	if (!local_buf) {
-		espi_trans->status = -ENOMEM;
-		return;
-	}
-
 	list_for_each_entry(t, &m->transfers, transfer_list) {
 		if (t->tx_buf) {
 			memcpy(local_buf + i, t->tx_buf, t->len);
@@ -355,16 +351,17 @@ static void fsl_espi_cmd_trans(struct sp
 	fsl_espi_do_trans(m, espi_trans);
 
 	espi_trans->actual_length = espi_trans->len;
-	kfree(local_buf);
 }
 
 static void fsl_espi_rw_trans(struct spi_message *m,
 				struct fsl_espi_transfer *trans, u8 *rx_buff)
 {
+	struct spi_device *spi = m->spi;
+	struct mpc8xxx_spi *mspi = spi_master_get_devdata(spi->master);
 	struct fsl_espi_transfer *espi_trans = trans;
 	unsigned int total_len = espi_trans->len;
 	struct spi_transfer *t;
-	u8 *local_buf;
+	u8 *local_buf = mspi->local_buf;
 	u8 *rx_buf = rx_buff;
 	unsigned int trans_len;
 	unsigned int addr;
@@ -373,12 +370,6 @@ static void fsl_espi_rw_trans(struct spi
 	unsigned int pos;
 	int i, loop;
 
-	local_buf = kzalloc(SPCOM_TRANLEN_MAX, GFP_KERNEL);
-	if (!local_buf) {
-		espi_trans->status = -ENOMEM;
-		return;
-	}
-
 	for (pos = 0, loop = 0; pos < total_len; pos += trans_len, loop++) {
 		trans_len = total_len - pos;
 
@@ -424,8 +415,6 @@ static void fsl_espi_rw_trans(struct spi
 		else
 			espi_trans->actual_length += espi_trans->len;
 	}
-
-	kfree(local_buf);
 }
 
 static int fsl_espi_do_one_msg(struct spi_master *master,
@@ -673,6 +662,12 @@ static struct spi_master * fsl_espi_prob
 
 	mpc8xxx_spi = spi_master_get_devdata(master);
 
+	mpc8xxx_spi->local_buf = devm_kzalloc(dev, SPCOM_TRANLEN_MAX, GFP_KERNEL);
+	if (!mpc8xxx_spi->local_buf) {
+		ret = -ENOMEM;
+		goto err_probe;
+	}
+
 	mpc8xxx_spi->reg_base = devm_ioremap_resource(dev, mem);
 	if (IS_ERR(mpc8xxx_spi->reg_base)) {
 		ret = PTR_ERR(mpc8xxx_spi->reg_base);
--- a/drivers/spi/spi-fsl-lib.h
+++ b/drivers/spi/spi-fsl-lib.h
@@ -30,6 +30,7 @@ struct mpc8xxx_spi {
 	void *rx;
 #if IS_ENABLED(CONFIG_SPI_FSL_ESPI)
 	int len;
+	u8 *local_buf;
 #endif
 
 	int subblock;