From: Liem Date: Mon, 29 Jun 2026 02:38:28 +0000 (+0800) Subject: i2c: imx: Fix slave registration race and error handling X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d64ec362c369bbc33833f7936d5f3a706b0d5c45;p=thirdparty%2Flinux.git i2c: imx: Fix slave registration race and error handling In i2c_imx_reg_slave(), the slave pointer was assigned before pm_runtime_resume_and_get(). If pm_runtime_resume_and_get() failed, the error path returned without clearing i2c_imx->slave, leaving it non-NULL and causing all subsequent registration attempts to fail with -EBUSY. Additionally, because this driver uses a shared IRQ, the interrupt handler i2c_imx_isr() can execute concurrently and, after acquiring slave_lock, dereference i2c_imx->slave. The previous fix attempt added a lockless i2c_imx->slave = NULL on the error path, but that could race with the ISR under the lock and still cause a NULL pointer dereference. Fix both issues by deferring the assignment of i2c_imx->slave and i2c_imx->last_slave_event to after a successful resume, and by performing the assignment inside the slave_lock critical section. This guarantees that the slave pointer is never left stale on the error path and is always valid when observed by the interrupt handler. Fixes: f7414cd6923f ("i2c: imx: support slave mode for imx I2C driver") Signed-off-by: Liem Cc: # v5.11+ Reviewed-by: Frank Li Acked-by: Carlos Song Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20260629023829.152651-2-liem16213@gmail.com --- diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index d549d630b41a..49859ee494c6 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -930,9 +930,6 @@ static int i2c_imx_reg_slave(struct i2c_client *client) if (i2c_imx->slave) return -EBUSY; - i2c_imx->slave = client; - i2c_imx->last_slave_event = I2C_SLAVE_STOP; - /* Resume */ ret = pm_runtime_resume_and_get(i2c_imx->adapter.dev.parent); if (ret < 0) { @@ -940,6 +937,11 @@ static int i2c_imx_reg_slave(struct i2c_client *client) return ret; } + scoped_guard(spinlock_irqsave, &i2c_imx->slave_lock) { + i2c_imx->slave = client; + i2c_imx->last_slave_event = I2C_SLAVE_STOP; + } + i2c_imx_slave_init(i2c_imx); return 0;