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d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=uA/tElCwH30ICqo0HsDr0006JRE1RTl1ltyIJoP+IYs=; b=eVgf+IsKTZDIxcCij3S03QxOdqrpyDwYW2M/mkti0CtAuVuHmoLwt1LJjrvVEtg8mX TTE/VXDch2bsW5flCECSBTPC7eb9tZRODlPuxPMAE1o0zZQ6Fjb0ovlQ3c9re0cqK87x FEUUX37WLsJhTw//L6FGWsNgRx5rcnnWH+ZsT0j3EkbXOAERqFr2Am7k5kbaYuC0hukx HzH46Lzz3n8yyj1zhL6KiFFPK49T3fPY+SKVs/dSlbEl2PAtc1HXtOoGwmLgz4vM2M+/ m6xPbpNGjcpFpTNTKq+Cn3ShhRpc9DAfvfIPdiYl+QapL64Nq0KTWaOUxoj8aYD5S2VL ulOg== X-Gm-Message-State: AOAM533wdB00CZhMFrHoB19PB4pfjF3DaZx+T09p/12iaXSlyCFsF/zg IBEb4CJBhPQrbIaV4xKe7hDlVrOLipKGOPMdUuBvOw== X-Google-Smtp-Source: ABdhPJwPQScejqOcNk37vjQoYZiYu9cG/oplCTLUp7LUHByI5OAlsR9eWwwDdsRm0CdypE/Fwft/tJHaTL+P6CmCMxg= X-Received: by 2002:a19:fc14:: with SMTP id a20mr429329lfi.0.1595145573696; Sun, 19 Jul 2020 00:59:33 -0700 (PDT) MIME-Version: 1.0 References: <1595115599-100054-1-git-send-email-dphadke@linux.microsoft.com> In-Reply-To: <1595115599-100054-1-git-send-email-dphadke@linux.microsoft.com> From: Rayagonda Kokatanur Date: Sun, 19 Jul 2020 13:29:21 +0530 Message-ID: Subject: Re: [PATCH] i2c: iproc: fix race between client unreg and isr To: Dhananjay Phadke Cc: linux-i2c , Linux Kernel Mailing List , Wolfram Sang , Ray Jui , BCM Kernel Feedback Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jul 19, 2020 at 5:10 AM Dhananjay Phadke wrote: > > When i2c client unregisters, synchronize irq before setting > iproc_i2c->slave to NULL. > > Unable to handle kernel NULL pointer dereference at virtual address 0000000000000318 > > [ 371.020421] pc : bcm_iproc_i2c_isr+0x530/0x11f0 > [ 371.025098] lr : __handle_irq_event_percpu+0x6c/0x170 > [ 371.030309] sp : ffff800010003e40 > [ 371.033727] x29: ffff800010003e40 x28: 0000000000000060 > [ 371.039206] x27: ffff800010ca9de0 x26: ffff800010f895df > [ 371.044686] x25: ffff800010f18888 x24: ffff0008f7ff3600 > [ 371.050165] x23: 0000000000000003 x22: 0000000001600000 > [ 371.055645] x21: ffff800010f18888 x20: 0000000001600000 > [ 371.061124] x19: ffff0008f726f080 x18: 0000000000000000 > [ 371.066603] x17: 0000000000000000 x16: 0000000000000000 > [ 371.072082] x15: 0000000000000000 x14: 0000000000000000 > [ 371.077561] x13: 0000000000000000 x12: 0000000000000001 > [ 371.083040] x11: 0000000000000000 x10: 0000000000000040 > [ 371.088519] x9 : ffff800010f317c8 x8 : ffff800010f317c0 > [ 371.093999] x7 : ffff0008f805b3b0 x6 : 0000000000000000 > [ 371.099478] x5 : ffff0008f7ff36a4 x4 : ffff8008ee43d000 > [ 371.104957] x3 : 0000000000000000 x2 : ffff8000107d64c0 > [ 371.110436] x1 : 00000000c00000af x0 : 0000000000000000 > > [ 371.115916] Call trace: > [ 371.118439] bcm_iproc_i2c_isr+0x530/0x11f0 > [ 371.122754] __handle_irq_event_percpu+0x6c/0x170 > [ 371.127606] handle_irq_event_percpu+0x34/0x88 > [ 371.132189] handle_irq_event+0x40/0x120 > [ 371.136234] handle_fasteoi_irq+0xcc/0x1a0 > [ 371.140459] generic_handle_irq+0x24/0x38 > [ 371.144594] __handle_domain_irq+0x60/0xb8 > [ 371.148820] gic_handle_irq+0xc0/0x158 > [ 371.152687] el1_irq+0xb8/0x140 > [ 371.155927] arch_cpu_idle+0x10/0x18 > [ 371.159615] do_idle+0x204/0x290 > [ 371.162943] cpu_startup_entry+0x24/0x60 > [ 371.166990] rest_init+0xb0/0xbc > [ 371.170322] arch_call_rest_init+0xc/0x14 > [ 371.174458] start_kernel+0x404/0x430 > > Fixes: c245d94ed106 ("i2c: iproc: Add multi byte read-write support for slave mode") > Signed-off-by: Dhananjay Phadke > --- > drivers/i2c/busses/i2c-bcm-iproc.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c > index b58224b7b..37d2a79e7 100644 > --- a/drivers/i2c/busses/i2c-bcm-iproc.c > +++ b/drivers/i2c/busses/i2c-bcm-iproc.c > @@ -1074,14 +1074,15 @@ static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave) > if (!iproc_i2c->slave) > return -EINVAL; > > - iproc_i2c->slave = NULL; > - > /* disable all slave interrupts */ > tmp = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET); > tmp &= ~(IE_S_ALL_INTERRUPT_MASK << > IE_S_ALL_INTERRUPT_SHIFT); > iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, tmp); > > + synchronize_irq(iproc_i2c->irq); > + iproc_i2c->slave = NULL; > + > /* Erase the slave address programmed */ > tmp = iproc_i2c_rd_reg(iproc_i2c, S_CFG_SMBUS_ADDR_OFFSET); > tmp &= ~BIT(S_CFG_EN_NIC_SMB_ADDR3_SHIFT); Looks good to me. Thank you for the patch. Reviewed-by: Rayagonda Kokatanur Regards, Rayagonda