Merge tag 'mtd/for-4.19' of git://git.infradead.org/linux-mtd

Pull mtd updates from Boris Brezillon:
 "JFFS2 changes:
   - Support 64-bit timestamps

  MTD core changes:
   - Support sub-partitions
   - Clarify mtd_oob_ops documentation
   - Make Kconfig formatting consistent
   - Fix potential overflows in mtdchar_{write,read}()
   - Fallback to ->_{read,write}() when ->_{read,write}_oob() is missing
     and no OOB data were requested
   - Remove VLA usage in the bch lib

  MTD driver changes:
   - Use mtd_device_register() instead of mtd_device_parse_register()
     where applicable
   - Use proper printk format to print physical addresses in the
     solutionengine driver
   - Add missing mtd_set_of_node() call in the powernv driver
   - Remove unneeded variables in a few drivers
   - Plug the TRX part parser to the DT partition parsers logic
   - Check ioremap_cache() return code in the gpio-addr-flash driver
   - Stop using VMLINUX_SYMBOL_STR() in gen_probe.c

  SPI NOR core changes:
   - Apply reset hacks only when reset is explicitly marked as broken in
     the DT

   SPI NOR driver changes:
   - Minor cleanup/fixes in the m25p80 driver
   - Release flash_np in the nxp-spifi driver
   - Add suspend/resume hooks to the atmel-quadspi driver
   - Include gpio/consumer.h instead of gpio.h in the atmel-quadspi
     driver
   - Use %pK instead of %p in the stm32-quadspi driver
   - Improve timeout handling in the cadence-quadspi driver
   - Use mtd_device_register() instead of mtd_device_parse_register() in
     the intel-spi driver

  NAND core changes:
   - Add the SPI-NAND framework.
   - Create a helper to find the best ECC configuration.
   - Create NAND controller operations.
   - Allocate dynamically ONFI parameters structure.
   - Add defines for ONFI version bits.
   - Add manufacturer fixup for ONFI parameter page.
   - Add an option to specify NAND chip as a boot device.
   - Add Reed-Solomon error correction algorithm.
   - Better name for the controller structure.
   - Remove unused caller_is_module() definition.
   - Make subop helpers return unsigned values.
   - Expose _notsupp() helpers for raw page accessors.
   - Add default values for dynamic timings.
   - Kill the chip->scan_bbt() hook.
   - Rename nand_default_bbt() into nand_create_bbt().
   - Start to clean the nand_chip structure.
   - Remove stale prototype from rawnand.h.

  Raw NAND controllers drivers changes:
   - Qcom: structuring cleanup.
   - Denali: use core helper to find the best ECC configuration.
   - Possible build of almost all drivers by adding a dependency on
     COMPILE_TEST for almost all of them in Kconfig, implies various
     fixes, Kconfig cleanup, GPIO headers inclusion cleanup, and even
     changes in sparc64 and ia64 architectures.
   - Clean the ->probe() functions error path of a lot of drivers.
   - Migrate all drivers to use nand_scan() instead of
     nand_scan_ident()/nand_scan_tail() pair.
   - Use mtd_device_register() where applicable to simplify the code.
   - Marvell:
      * Handle on-die ECC.
      * Better clocks handling.
      * Remove bogus comment.
      * Add suspend and resume support.
   - Tegra: add NAND controller driver.
   - Atmel:
      * Add module param to avoid using dma.
      * Drop Wenyou Yang from MAINTAINERS.
   - Denali: optimize timings handling.
   - FSMC: Stop using chip->read_buf().
   - FSL:
      * Switch to SPDX license tag identifiers.
      * Fix qualifiers in MXC init functions.

  Raw NAND chip drivers changes:
   - Micron:
      * Add fixup for ONFI revision.
      * Update ecc_stats.corrected.
      * Make ECC activation stateful.
      * Avoid enabling/disabling ECC when it can't be disabled.
      * Get the actual number of bitflips.
      * Allow forced on-die ECC.
      * Support 8/512 on-die ECC.
      * Fix on-die ECC detection logic.
   - Hynix:
      * Fix decoding the OOB size on H27UCG8T2BTR.
      * Use ->exec_op() in hynix_nand_reg_write_op()"

* tag 'mtd/for-4.19' of git://git.infradead.org/linux-mtd: (188 commits)
  mtd: rawnand: atmel: Select GENERIC_ALLOCATOR
  MAINTAINERS: drop Wenyou Yang from Atmel NAND driver support
  mtd: rawnand: allocate dynamically ONFI parameters during detection
  mtd: spi-nor: only apply reset hacks to broken hardware
  mtd: spi-nor: cadence-quadspi: fix timeout handling
  mtd: spi-nor: atmel-quadspi: Include gpio/consumer.h instead of gpio.h
  mtd: spi-nor: intel-spi: use mtd_device_register()
  mtd: spi-nor: stm32-quadspi: replace "%p" with "%pK"
  mtd: spi-nor: atmel-quadspi: add suspend/resume hooks
  mtd: rawnand: allocate model parameter dynamically
  mtd: rawnand: do not export nand_scan_[ident|tail]() anymore
  mtd: rawnand: txx9ndfmc: convert driver to nand_scan()
  mtd: rawnand: txx9ndfmc: clarify ECC parameters assignation
  mtd: rawnand: tegra: convert driver to nand_scan()
  mtd: rawnand: jz4740: convert driver to nand_scan()
  mtd: rawnand: jz4740: group nand_scan_{ident, tail} calls
  mtd: rawnand: jz4740: fix probe function error path
  mtd: rawnand: docg4: convert driver to nand_scan()
  mtd: rawnand: do not execute nand_scan_ident() if maxchips is zero
  mtd: rawnand: atmel: convert driver to nand_scan()
  ...

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index cd67c85cc87d..02389528f622 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -160,8 +160,12 @@ static ssize_t mtdchar_read(struct file *file, char __user *buf, size_t count,
 
 	pr_debug("MTD_read\n");
 
-	if (*ppos + count > mtd->size)
-		count = mtd->size - *ppos;
+	if (*ppos + count > mtd->size) {
+		if (*ppos < mtd->size)
+			count = mtd->size - *ppos;
+		else
+			count = 0;
+	}
 
 	if (!count)
 		return 0;
@@ -246,7 +250,7 @@ static ssize_t mtdchar_write(struct file *file, const char __user *buf, size_t c
 
 	pr_debug("MTD_write\n");
 
-	if (*ppos == mtd->size)
+	if (*ppos >= mtd->size)
 		return -ENOSPC;
 
 	if (*ppos + count > mtd->size)