From f1fdcbbdf45d9609f3d4063b67e9ea941ba3a58f Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 16 Oct 2018 12:01:47 +0900 Subject: [PATCH] i2c: uniphier-f: make driver robust against concurrency This is unlikely to happen, but it is possible for a CPU to enter the interrupt handler just after wait_for_completion_timeout() has expired. If this happens, the hardware is accessed from multiple contexts concurrently. Disable the IRQ after wait_for_completion_timeout(), and do nothing from the handler when the IRQ is disabled. Fixes: 6a62974b667f ("i2c: uniphier_f: add UniPhier FIFO-builtin I2C driver") Signed-off-by: Masahiro Yamada Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-uniphier-f.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c index a403e8579b65..200dfd1771af 100644 --- a/drivers/i2c/busses/i2c-uniphier-f.c +++ b/drivers/i2c/busses/i2c-uniphier-f.c @@ -98,6 +98,7 @@ struct uniphier_fi2c_priv { unsigned int flags; unsigned int busy_cnt; unsigned int clk_cycle; + spinlock_t lock; /* IRQ synchronization */ }; static void uniphier_fi2c_fill_txfifo(struct uniphier_fi2c_priv *priv, @@ -162,7 +163,10 @@ static irqreturn_t uniphier_fi2c_interrupt(int irq, void *dev_id) struct uniphier_fi2c_priv *priv = dev_id; u32 irq_status; + spin_lock(&priv->lock); + irq_status = readl(priv->membase + UNIPHIER_FI2C_INT); + irq_status &= priv->enabled_irqs; dev_dbg(&priv->adap.dev, "interrupt: enabled_irqs=%04x, irq_status=%04x\n", @@ -230,6 +234,8 @@ static irqreturn_t uniphier_fi2c_interrupt(int irq, void *dev_id) goto handled; } + spin_unlock(&priv->lock); + return IRQ_NONE; data_done: @@ -246,6 +252,8 @@ complete: handled: uniphier_fi2c_clear_irqs(priv); + spin_unlock(&priv->lock); + return IRQ_HANDLED; } @@ -311,7 +319,7 @@ static int uniphier_fi2c_master_xfer_one(struct i2c_adapter *adap, { struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap); bool is_read = msg->flags & I2C_M_RD; - unsigned long time_left; + unsigned long time_left, flags; dev_dbg(&adap->dev, "%s: addr=0x%02x, len=%d, stop=%d\n", is_read ? "receive" : "transmit", msg->addr, msg->len, stop); @@ -342,6 +350,12 @@ static int uniphier_fi2c_master_xfer_one(struct i2c_adapter *adap, priv->membase + UNIPHIER_FI2C_CR); time_left = wait_for_completion_timeout(&priv->comp, adap->timeout); + + spin_lock_irqsave(&priv->lock, flags); + priv->enabled_irqs = 0; + uniphier_fi2c_set_irqs(priv); + spin_unlock_irqrestore(&priv->lock, flags); + if (!time_left) { dev_err(&adap->dev, "transaction timeout.\n"); uniphier_fi2c_recover(priv); @@ -529,6 +543,7 @@ static int uniphier_fi2c_probe(struct platform_device *pdev) priv->clk_cycle = clk_rate / bus_speed; init_completion(&priv->comp); + spin_lock_init(&priv->lock); priv->adap.owner = THIS_MODULE; priv->adap.algo = &uniphier_fi2c_algo; priv->adap.dev.parent = dev;