mmc: tmio: fix recursive spinlock, don't schedule with interrupts disabled

Calling mmc_request_done() under a spinlock with interrupts disabled
leads to a recursive spin-lock on request retry path and to
scheduling in atomic context. This patch fixes both these problems
by moving mmc_request_done() to the scheduler workqueue.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>

diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
index 211ef6e..f0d7c43 100644 (file)
--- a/drivers/mmc/host/tmio_mmc.h
+++ b/drivers/mmc/host/tmio_mmc.h
@@ -18,6 +18,7 @@
 
 #include <linux/highmem.h>
 #include <linux/mmc/tmio.h>
+#include <linux/mutex.h>
 #include <linux/pagemap.h>
 #include <linux/spinlock.h>
 
@@ -73,8 +74,11 @@ struct tmio_mmc_host {
 
        /* Track lost interrupts */
        struct delayed_work     delayed_reset_work;
-       spinlock_t              lock;
+       struct work_struct      done;
+
+       spinlock_t              lock;           /* protect host private data */
        unsigned long           last_req_ts;
+       struct mutex            ios_lock;       /* protect set_ios() context */
 };
 
 int tmio_mmc_host_probe(struct tmio_mmc_host **host,

diff --git a/drivers/mmc/host/tmio_mmc_pio.c b/drivers/mmc/host/tmio_mmc_pio.c
index f7dd3b1..a2f76ad 100644 (file)
--- a/drivers/mmc/host/tmio_mmc_pio.c
+++ b/drivers/mmc/host/tmio_mmc_pio.c
@@ -250,10 +250,16 @@ static void tmio_mmc_reset_work(struct work_struct *work)
 /* called with host->lock held, interrupts disabled */
 static void tmio_mmc_finish_request(struct tmio_mmc_host *host)
 {
-       struct mmc_request *mrq = host->mrq;
+       struct mmc_request *mrq;
+       unsigned long flags;
 
-       if (!mrq)
+       spin_lock_irqsave(&host->lock, flags);
+
+       mrq = host->mrq;
+       if (IS_ERR_OR_NULL(mrq)) {
+               spin_unlock_irqrestore(&host->lock, flags);
                return;
+       }
 
        host->cmd = NULL;
        host->data = NULL;
@@ -262,11 +268,18 @@ static void tmio_mmc_finish_request(struct tmio_mmc_host *host)
        cancel_delayed_work(&host->delayed_reset_work);
 
        host->mrq = NULL;
+       spin_unlock_irqrestore(&host->lock, flags);
 
-       /* FIXME: mmc_request_done() can schedule! */
        mmc_request_done(host->mmc, mrq);
 }
 
+static void tmio_mmc_done_work(struct work_struct *work)
+{
+       struct tmio_mmc_host *host = container_of(work, struct tmio_mmc_host,
+                                                 done);
+       tmio_mmc_finish_request(host);
+}
+
 /* These are the bitmasks the tmio chip requires to implement the MMC response
  * types. Note that R1 and R6 are the same in this scheme. */
 #define APP_CMD        0x0040
@@ -433,7 +446,7 @@ void tmio_mmc_do_data_irq(struct tmio_mmc_host *host)
                        BUG();
        }
 
-       tmio_mmc_finish_request(host);
+       schedule_work(&host->done);
 }
 
 static void tmio_mmc_data_irq(struct tmio_mmc_host *host)
@@ -523,7 +536,7 @@ static void tmio_mmc_cmd_irq(struct tmio_mmc_host *host,
                                tasklet_schedule(&host->dma_issue);
                }
        } else {
-               tmio_mmc_finish_request(host);
+               schedule_work(&host->done);
        }
 
 out:
@@ -573,7 +586,8 @@ irqreturn_t tmio_mmc_irq(int irq, void *devid)
        if (ireg & (TMIO_STAT_CARD_INSERT | TMIO_STAT_CARD_REMOVE)) {
                tmio_mmc_ack_mmc_irqs(host, TMIO_STAT_CARD_INSERT |
                        TMIO_STAT_CARD_REMOVE);
-               mmc_detect_change(host->mmc, msecs_to_jiffies(100));
+               if (!work_pending(&host->mmc->detect.work))
+                       mmc_detect_change(host->mmc, msecs_to_jiffies(100));
                goto out;
        }
 
@@ -703,6 +717,8 @@ static void tmio_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
        struct tmio_mmc_data *pdata = host->pdata;
        unsigned long flags;
 
+       mutex_lock(&host->ios_lock);
+
        spin_lock_irqsave(&host->lock, flags);
        if (host->mrq) {
                if (IS_ERR(host->mrq)) {
@@ -718,6 +734,8 @@ static void tmio_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
                                host->mrq->cmd->opcode, host->last_req_ts, jiffies);
                }
                spin_unlock_irqrestore(&host->lock, flags);
+
+               mutex_unlock(&host->ios_lock);
                return;
        }
 
@@ -771,6 +789,8 @@ static void tmio_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
                        current->comm, task_pid_nr(current),
                        ios->clock, ios->power_mode);
        host->mrq = NULL;
+
+       mutex_unlock(&host->ios_lock);
 }
 
 static int tmio_mmc_get_ro(struct mmc_host *mmc)
@@ -867,9 +887,11 @@ int __devinit tmio_mmc_host_probe(struct tmio_mmc_host **host,
                tmio_mmc_enable_sdio_irq(mmc, 0);
 
        spin_lock_init(&_host->lock);
+       mutex_init(&_host->ios_lock);
 
        /* Init delayed work for request timeouts */
        INIT_DELAYED_WORK(&_host->delayed_reset_work, tmio_mmc_reset_work);
+       INIT_WORK(&_host->done, tmio_mmc_done_work);
 
        /* See if we also get DMA */
        tmio_mmc_request_dma(_host, pdata);
@@ -917,6 +939,7 @@ void tmio_mmc_host_remove(struct tmio_mmc_host *host)
                pm_runtime_get_sync(&pdev->dev);
 
        mmc_remove_host(host->mmc);
+       cancel_work_sync(&host->done);
        cancel_delayed_work_sync(&host->delayed_reset_work);
        tmio_mmc_release_dma(host);