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Subject: Re: [PATCH 1/1] mmc: cqhci: fix random crash when remove mmc module
To:     Frank Li <lznuaa@gmail.com>, riteshh@codeaurora.org,
        asutoshd@codeaurora.org, ulf.hansson@linaro.org,
        linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
        haibo.chen@nxp.com
References: <20210301172151.281814-1-Frank.Li@nxp.com>
From:   Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
 Business Identity Code: 0357606 - 4, Domiciled in Helsinki
Message-ID: <0d135a2b-02d0-f05b-918b-c4253d67caf9@intel.com>
Date:   Tue, 2 Mar 2021 09:04:03 +0200
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On 1/03/21 7:21 pm, Frank Li wrote:
> [ 6684.493350] Unable to handle kernel paging request at virtual address ffff800011c5b0f0
> [ 6684.498531] mmc0: card 0001 removed
> [ 6684.501556] Mem abort info:
> [ 6684.509681]   ESR = 0x96000047
> [ 6684.512786]   EC = 0x25: DABT (current EL), IL = 32 bits
> [ 6684.518394]   SET = 0, FnV = 0
> [ 6684.521707]   EA = 0, S1PTW = 0
> [ 6684.524998] Data abort info:
> [ 6684.528236]   ISV = 0, ISS = 0x00000047
> [ 6684.532986]   CM = 0, WnR = 1
> [ 6684.536129] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000081b22000
> [ 6684.543923] [ffff800011c5b0f0] pgd=00000000bffff003, p4d=00000000bffff003, pud=00000000bfffe003, pmd=00000000900e1003, pte=0000000000000000
> [ 6684.557915] Internal error: Oops: 96000047 [#1] PREEMPT SMP
> [ 6684.564240] Modules linked in: sdhci_esdhc_imx(-) sdhci_pltfm sdhci cqhci mmc_block mmc_core fsl_jr_uio caam_jr caamkeyblob_desc caamhash_desc caamalg_desc crypto_engine rng_core authenc libdes crct10dif_ce flexcan can_dev caam error [last unloaded: mmc_core]
> [ 6684.587281] CPU: 0 PID: 79138 Comm: kworker/0:3H Not tainted 5.10.9-01410-g3ba33182767b-dirty #10
> [ 6684.596160] Hardware name: Freescale i.MX8DXL EVK (DT)
> [ 6684.601320] Workqueue: kblockd blk_mq_run_work_fn
> 
> [ 6684.606094] pstate: 40000005 (nZcv daif -PAN -UAO -TCO BTYPE=--)
> [ 6684.612286] pc : cqhci_request+0x148/0x4e8 [cqhci]
> ^GMessage from syslogd@  at Thu Jan  1 01:51:24 1970 ...[ 6684.617085] lr : cqhci_request+0x314/0x4e8 [cqhci]
> [ 6684.626734] sp : ffff80001243b9f0
> [ 6684.630049] x29: ffff80001243b9f0 x28: ffff00002c3dd000
> [ 6684.635367] x27: 0000000000000001 x26: 0000000000000001
> [ 6684.640690] x25: ffff00002c451000 x24: 000000000000000f
> [ 6684.646007] x23: ffff000017e71c80 x22: ffff00002c451000
> [ 6684.651326] x21: ffff00002c0f3550 x20: ffff00002c0f3550
> [ 6684.656651] x19: ffff000017d46880 x18: ffff00002cea1500
> [ 6684.661977] x17: 0000000000000000 x16: 0000000000000000
> [ 6684.667294] x15: 000001ee628e3ed1 x14: 0000000000000278
> [ 6684.672610] x13: 0000000000000001 x12: 0000000000000001
> [ 6684.677927] x11: 0000000000000000 x10: 0000000000000000
> [ 6684.683243] x9 : 000000000000002b x8 : 0000000000001000
> [ 6684.688560] x7 : 0000000000000010 x6 : ffff00002c0f3678
> [ 6684.693886] x5 : 000000000000000f x4 : ffff800011c5b000
> [ 6684.699211] x3 : 000000000002d988 x2 : 0000000000000008
> [ 6684.704537] x1 : 00000000000000f0 x0 : 0002d9880008102f
> [ 6684.709854] Call trace:
> [ 6684.712313]  cqhci_request+0x148/0x4e8 [cqhci]
> [ 6684.716803]  mmc_cqe_start_req+0x58/0x68 [mmc_core]
> [ 6684.721698]  mmc_blk_mq_issue_rq+0x460/0x810 [mmc_block]
> [ 6684.727018]  mmc_mq_queue_rq+0x118/0x2b0 [mmc_block]
> 
> cqhci_request was called after cqhci_disable.
> 
> cqhci_disable                                 cqhci_request
> {                                             {
> 	dmam_free_coherent();  (1) free
>                                                   if(!cq_host->enable)
>                                                        return
> 				         (2) pass check here
> 	cq_host->enable = false;
> 
>                                                   task_desc= get_desc(cq_host,tag);
>                                                              ^^^^ crash here
>                                          (3) access memory which is already free
> 
> }                                             }
> 
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
>  drivers/mmc/host/cqhci-core.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mmc/host/cqhci-core.c b/drivers/mmc/host/cqhci-core.c
> index 93b0432bb601..36d292261e50 100644
> --- a/drivers/mmc/host/cqhci-core.c
> +++ b/drivers/mmc/host/cqhci-core.c
> @@ -389,6 +389,7 @@ static void cqhci_off(struct mmc_host *mmc)
>  static void cqhci_disable(struct mmc_host *mmc)
>  {
>  	struct cqhci_host *cq_host = mmc->cqe_private;
> +	unsigned long flags;
>  
>  	if (!cq_host->enabled)
>  		return;
> @@ -397,6 +398,11 @@ static void cqhci_disable(struct mmc_host *mmc)
>  
>  	__cqhci_disable(cq_host);
>  
> +	/* need wait for cqhci_request finish before free memory */
> +	spin_lock_irqsave(&cq_host->lock, flags);
> +	cq_host->enabled = false;
> +	spin_unlock_irqrestore(&cq_host->lock, flags);
> +
>  	dmam_free_coherent(mmc_dev(mmc), cq_host->data_size,
>  			   cq_host->trans_desc_base,
>  			   cq_host->trans_desc_dma_base);
> @@ -408,7 +414,6 @@ static void cqhci_disable(struct mmc_host *mmc)
>  	cq_host->trans_desc_base = NULL;
>  	cq_host->desc_base = NULL;
>  
> -	cq_host->enabled = false;
>  }
>  
>  static void cqhci_prep_task_desc(struct mmc_request *mrq,
> @@ -612,6 +617,13 @@ static int cqhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
>  			cq_host->ops->enable(mmc);
>  	}
>  
> +	spin_lock_irqsave(&cq_host->lock, flags);
> +	if (!cq_host->enabled) {
> +		pr_err("%s: cqhci: not enabled\n", mmc_hostname(mmc));
> +		err = -EINVAL;
> +		goto out_unlock;
> +	}
> +
>  	if (mrq->data) {
>  		cqhci_prep_task_desc(mrq, cq_host, tag);
>  
> @@ -619,14 +631,12 @@ static int cqhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
>  		if (err) {
>  			pr_err("%s: cqhci: failed to setup tx desc: %d\n",
>  			       mmc_hostname(mmc), err);
> -			return err;
> +			goto out_unlock;
>  		}
>  	} else {
>  		cqhci_prep_dcmd_desc(mmc, mrq);
>  	}
>  
> -	spin_lock_irqsave(&cq_host->lock, flags);
> -
>  	if (cq_host->recovery_halt) {
>  		err = -EBUSY;
>  		goto out_unlock;
> 

Please try the following instead:


diff --git a/drivers/mmc/core/bus.c b/drivers/mmc/core/bus.c
index c2e70b757dd1..dfc8d2877115 100644
--- a/drivers/mmc/core/bus.c
+++ b/drivers/mmc/core/bus.c
@@ -399,11 +399,6 @@ void mmc_remove_card(struct mmc_card *card)
 	mmc_remove_card_debugfs(card);
 #endif
 
-	if (host->cqe_enabled) {
-		host->cqe_ops->cqe_disable(host);
-		host->cqe_enabled = false;
-	}
-
 	if (mmc_card_present(card)) {
 		if (mmc_host_is_spi(card->host)) {
 			pr_info("%s: SPI card removed\n",
@@ -416,6 +411,11 @@ void mmc_remove_card(struct mmc_card *card)
 		of_node_put(card->dev.of_node);
 	}
 
+	if (host->cqe_enabled) {
+		host->cqe_ops->cqe_disable(host);
+		host->cqe_enabled = false;
+	}
+
 	put_device(&card->dev);
 }