linux-kernel - [PATCH] i2c: bcm-iproc: Fix bcm_iproc_i2c

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Message-ID: <TYCP286MB1188708B1CE64D95FBACF9E78A20A@TYCP286MB1188.JPNP286.PROD.OUTLOOK.COM>
Date:   Sat, 24 Jun 2023 19:36:02 +0000
From:   YE Chengfeng <cyeaa@...nect.ust.hk>
To:     "andi.shyti@...nel.org" <andi.shyti@...nel.org>,
        "rjui@...adcom.com" <rjui@...adcom.com>,
        "sbranden@...adcom.com" <sbranden@...adcom.com>
CC:     "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bcm-kernel-feedback-list@...adcom.com" 
        <bcm-kernel-feedback-list@...adcom.com>
Subject: [PATCH] i2c: bcm-iproc: Fix bcm_iproc_i2c_isr deadlock issue

iproc_i2c_rd_reg and iproc_i2c_wr_reg are called from both
interrupt context (e.g. bcm_iproc_i2c_isr) and process context
(e.g. bcm_iproc_i2c_suspend). Therefore, interrupts should be
disabled to avoid potential deadlock. To prevent this deadlock,
use spin_lock_irqsave.

Signed-off-by: Chengfeng Ye <cyeaa@...nect.ust.hk>
---
 drivers/i2c/busses/i2c-bcm-iproc.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index 85d8a6b04885..d02245e4db8c 100644
--- a/drivers/i2c/busses/i2c-bcm-iproc.c
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -233,13 +233,14 @@ static inline u32 iproc_i2c_rd_reg(struct bcm_iproc_i2c_dev *iproc_i2c,
                                   u32 offset)
 {
        u32 val;
+       unsigned long flags;

        if (iproc_i2c->idm_base) {
-               spin_lock(&iproc_i2c->idm_lock);
+               spin_lock_irqsave(&iproc_i2c->idm_lock, flags);
                writel(iproc_i2c->ape_addr_mask,
                       iproc_i2c->idm_base + IDM_CTRL_DIRECT_OFFSET);
                val = readl(iproc_i2c->base + offset);
-               spin_unlock(&iproc_i2c->idm_lock);
+               spin_unlock_irqrestore(&iproc_i2c->idm_lock, flags);
        } else {
                val = readl(iproc_i2c->base + offset);
        }
@@ -250,12 +251,13 @@ static inline u32 iproc_i2c_rd_reg(struct bcm_iproc_i2c_dev *iproc_i2c,
 static inline void iproc_i2c_wr_reg(struct bcm_iproc_i2c_dev *iproc_i2c,
                                    u32 offset, u32 val)
 {
+       unsigned long flags;
        if (iproc_i2c->idm_base) {
-               spin_lock(&iproc_i2c->idm_lock);
+               spin_lock_irqsave(&iproc_i2c->idm_lock, flags);
                writel(iproc_i2c->ape_addr_mask,
                       iproc_i2c->idm_base + IDM_CTRL_DIRECT_OFFSET);
                writel(val, iproc_i2c->base + offset);
-               spin_unlock(&iproc_i2c->idm_lock);
+               spin_unlock_irqrestore(&iproc_i2c->idm_lock, flags);
        } else {
                writel(val, iproc_i2c->base + offset);
        }
-- 
2.17.1