From 013e6292aaf5e4b083a50a0f9e17e93628616860 Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Tue, 20 Nov 2018 11:57:20 +0100 Subject: mtd: rawnand: Simplify the locking nand_get_device() was complex for apparently no good reason. Let's replace this locking scheme with 2 mutexes: one attached to the controller and another one attached to the chip. Every time the core calls nand_get_device(), it will first lock the chip and if the chip is not suspended, will then lock the controller. nand_release_device() will release both lock in the reverse order. nand_get_device() can sleep, just like the previous implementation, which means you should never call that from an atomic context. We also get rid of - the chip->state field, since all it was used for was flagging the chip as suspended. We replace it by a field called chip->suspended and directly set it from nand_suspend/resume() - the controller->wq and controller->active fields which are no longer needed since the new controller->lock (now a mutex) guarantees that all operations are serialized at the controller level - panic_nand_get_device() which would anyway be a no-op. Talking about panic write, I keep thinking the rawnand implementation is unsafe because there's not negotiation with the controller to know when it's actually done with it's previous operation. I don't intend to fix that here, but that's probably something we should look at, or maybe we should consider dropping the ->_panic_write() implementation Last important change to mention: we now return -EBUSY when someone tries to access a device that as been suspended, and propagate this error to the upper layer. Signed-off-by: Boris Brezillon Signed-off-by: Miquel Raynal --- drivers/mtd/nand/raw/nand_base.c | 111 ++++++++++++++++----------------------- 1 file changed, 45 insertions(+), 66 deletions(-) (limited to 'drivers/mtd') diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index cca4b24d2ffa..96cadead262e 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -278,11 +278,8 @@ EXPORT_SYMBOL_GPL(nand_deselect_target); static void nand_release_device(struct nand_chip *chip) { /* Release the controller and the chip */ - spin_lock(&chip->controller->lock); - chip->controller->active = NULL; - chip->state = FL_READY; - wake_up(&chip->controller->wq); - spin_unlock(&chip->controller->lock); + mutex_unlock(&chip->controller->lock); + mutex_unlock(&chip->lock); } /** @@ -330,58 +327,24 @@ static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs) return nand_block_bad(chip, ofs); } -/** - * panic_nand_get_device - [GENERIC] Get chip for selected access - * @chip: the nand chip descriptor - * @new_state: the state which is requested - * - * Used when in panic, no locks are taken. - */ -static void panic_nand_get_device(struct nand_chip *chip, int new_state) -{ - /* Hardware controller shared among independent devices */ - chip->controller->active = chip; - chip->state = new_state; -} - /** * nand_get_device - [GENERIC] Get chip for selected access * @chip: NAND chip structure - * @new_state: the state which is requested * - * Get the device and lock it for exclusive access + * Lock the device and its controller for exclusive access + * + * Return: -EBUSY if the chip has been suspended, 0 otherwise */ -static int -nand_get_device(struct nand_chip *chip, int new_state) +static int nand_get_device(struct nand_chip *chip) { - spinlock_t *lock = &chip->controller->lock; - wait_queue_head_t *wq = &chip->controller->wq; - DECLARE_WAITQUEUE(wait, current); -retry: - spin_lock(lock); - - /* Hardware controller shared among independent devices */ - if (!chip->controller->active) - chip->controller->active = chip; - - if (chip->controller->active == chip && chip->state == FL_READY) { - chip->state = new_state; - spin_unlock(lock); - return 0; - } - if (new_state == FL_PM_SUSPENDED) { - if (chip->controller->active->state == FL_PM_SUSPENDED) { - chip->state = FL_PM_SUSPENDED; - spin_unlock(lock); - return 0; - } + mutex_lock(&chip->lock); + if (chip->suspended) { + mutex_unlock(&chip->lock); + return -EBUSY; } - set_current_state(TASK_UNINTERRUPTIBLE); - add_wait_queue(wq, &wait); - spin_unlock(lock); - schedule(); - remove_wait_queue(wq, &wait); - goto retry; + mutex_lock(&chip->controller->lock); + + return 0; } /** @@ -602,7 +565,10 @@ static int nand_block_markbad_lowlevel(struct nand_chip *chip, loff_t ofs) nand_erase_nand(chip, &einfo, 0); /* Write bad block marker to OOB */ - nand_get_device(chip, FL_WRITING); + ret = nand_get_device(chip); + if (ret) + return ret; + ret = nand_markbad_bbm(chip, ofs); nand_release_device(chip); } @@ -3580,7 +3546,9 @@ static int nand_read_oob(struct mtd_info *mtd, loff_t from, ops->mode != MTD_OPS_RAW) return -ENOTSUPP; - nand_get_device(chip, FL_READING); + ret = nand_get_device(chip); + if (ret) + return ret; if (!ops->datbuf) ret = nand_do_read_oob(chip, from, ops); @@ -4099,9 +4067,6 @@ static int panic_nand_write(struct mtd_info *mtd, loff_t to, size_t len, struct mtd_oob_ops ops; int ret; - /* Grab the device */ - panic_nand_get_device(chip, FL_WRITING); - nand_select_target(chip, chipnr); /* Wait for the device to get ready */ @@ -4132,7 +4097,9 @@ static int nand_write_oob(struct mtd_info *mtd, loff_t to, ops->retlen = 0; - nand_get_device(chip, FL_WRITING); + ret = nand_get_device(chip); + if (ret) + return ret; switch (ops->mode) { case MTD_OPS_PLACE_OOB: @@ -4205,7 +4172,9 @@ int nand_erase_nand(struct nand_chip *chip, struct erase_info *instr, return -EINVAL; /* Grab the lock and see if the device is available */ - nand_get_device(chip, FL_ERASING); + ret = nand_get_device(chip); + if (ret) + return ret; /* Shift to get first page */ page = (int)(instr->addr >> chip->page_shift); @@ -4298,7 +4267,7 @@ static void nand_sync(struct mtd_info *mtd) pr_debug("%s: called\n", __func__); /* Grab the lock and see if the device is available */ - nand_get_device(chip, FL_SYNCING); + WARN_ON(nand_get_device(chip)); /* Release it and go back */ nand_release_device(chip); } @@ -4315,7 +4284,10 @@ static int nand_block_isbad(struct mtd_info *mtd, loff_t offs) int ret; /* Select the NAND device */ - nand_get_device(chip, FL_READING); + ret = nand_get_device(chip); + if (ret) + return ret; + nand_select_target(chip, chipnr); ret = nand_block_checkbad(chip, offs, 0); @@ -4388,7 +4360,13 @@ static int nand_max_bad_blocks(struct mtd_info *mtd, loff_t ofs, size_t len) */ static int nand_suspend(struct mtd_info *mtd) { - return nand_get_device(mtd_to_nand(mtd), FL_PM_SUSPENDED); + struct nand_chip *chip = mtd_to_nand(mtd); + + mutex_lock(&chip->lock); + chip->suspended = 1; + mutex_unlock(&chip->lock); + + return 0; } /** @@ -4399,11 +4377,13 @@ static void nand_resume(struct mtd_info *mtd) { struct nand_chip *chip = mtd_to_nand(mtd); - if (chip->state == FL_PM_SUSPENDED) - nand_release_device(chip); + mutex_lock(&chip->lock); + if (chip->suspended) + chip->suspended = 0; else pr_err("%s called for a chip which is not in suspended state\n", __func__); + mutex_unlock(&chip->lock); } /** @@ -4413,7 +4393,7 @@ static void nand_resume(struct mtd_info *mtd) */ static void nand_shutdown(struct mtd_info *mtd) { - nand_get_device(mtd_to_nand(mtd), FL_PM_SUSPENDED); + nand_suspend(mtd); } /* Set default functions */ @@ -5018,6 +4998,8 @@ static int nand_scan_ident(struct nand_chip *chip, unsigned int maxchips, /* Assume all dies are deselected when we enter nand_scan_ident(). */ chip->cur_cs = -1; + mutex_init(&chip->lock); + /* Enforce the right timings for reset/detection */ onfi_fill_data_interface(chip, NAND_SDR_IFACE, 0); @@ -5717,9 +5699,6 @@ static int nand_scan_tail(struct nand_chip *chip) } chip->subpagesize = mtd->writesize >> mtd->subpage_sft; - /* Initialize state */ - chip->state = FL_READY; - /* Invalidate the pagebuffer reference */ chip->pagebuf = -1; -- cgit