The MMC subsystem does not guarantee, that host driver .request() and
.set_ios() callbacks are serialised. Such concurrent calls, however,
do not have to be meaningfully supported, drivers just have to make
sure to avoid any severe problems.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
---
drivers/mmc/host/tmio_mmc.h | 1 +
drivers/mmc/host/tmio_mmc_pio.c | 62 +++++++++++++++++++++++++++++++++++----
2 files changed, 57 insertions(+), 6 deletions(-)
diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
index 099ed49..f353624 100644
--- a/drivers/mmc/host/tmio_mmc.h
+++ b/drivers/mmc/host/tmio_mmc.h
@@ -19,6 +19,7 @@
#include <linux/highmem.h>
#include <linux/mmc/tmio.h>
#include <linux/pagemap.h>
+#include <linux/spinlock.h>
/* Definitions for values the CTRL_SDIO_STATUS register can take. */
#define TMIO_SDIO_STAT_IOIRQ 0x0001
diff --git a/drivers/mmc/host/tmio_mmc_pio.c b/drivers/mmc/host/tmio_mmc_pio.c
index 62d37de..6e3271d 100644
--- a/drivers/mmc/host/tmio_mmc_pio.c
+++ b/drivers/mmc/host/tmio_mmc_pio.c
@@ -243,8 +243,12 @@ static void tmio_mmc_reset_work(struct work_struct *work)
spin_lock_irqsave(&host->lock, flags);
mrq = host->mrq;
- /* request already finished */
- if (!mrq
+ /*
+ * is request already finished? Since we use a non-blocking
+ * cancel_delayed_work(), it can happen, that a .set_ios() call preempts
+ * us, so, have to check for IS_ERR(host->mrq)
+ */
+ if (IS_ERR_OR_NULL(mrq)
|| time_is_after_jiffies(host->last_req_ts +
msecs_to_jiffies(2000))) {
spin_unlock_irqrestore(&host->lock, flags);
@@ -264,16 +268,19 @@ static void tmio_mmc_reset_work(struct work_struct *work)
host->cmd = NULL;
host->data = NULL;
- host->mrq = NULL;
host->force_pio = false;
spin_unlock_irqrestore(&host->lock, flags);
tmio_mmc_reset(host);
+ /* Ready for new calls */
+ host->mrq = NULL;
+
mmc_request_done(host->mmc, mrq);
}
+/* called with host->lock held, interrupts disabled */
static void tmio_mmc_finish_request(struct tmio_mmc_host *host)
{
struct mmc_request *mrq = host->mrq;
@@ -281,13 +288,15 @@ static void tmio_mmc_finish_request(struct tmio_mmc_host *host)
if (!mrq)
return;
- host->mrq = NULL;
host->cmd = NULL;
host->data = NULL;
host->force_pio = false;
cancel_delayed_work(&host->delayed_reset_work);
+ host->mrq = NULL;
+
+ /* FIXME: mmc_request_done() can schedule! */
mmc_request_done(host->mmc, mrq);
}
@@ -685,15 +694,27 @@ static int tmio_mmc_start_data(struct tmio_mmc_host *host,
static void tmio_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
{
struct tmio_mmc_host *host = mmc_priv(mmc);
+ unsigned long flags;
int ret;
- if (host->mrq)
+ spin_lock_irqsave(&host->lock, flags);
+
+ if (host->mrq) {
pr_debug("request not null\n");
+ if (IS_ERR(host->mrq)) {
+ spin_unlock_irqrestore(&host->lock, flags);
+ mrq->cmd->error = -EAGAIN;
+ mmc_request_done(mmc, mrq);
+ return;
+ }
+ }
host->last_req_ts = jiffies;
wmb();
host->mrq = mrq;
+ spin_unlock_irqrestore(&host->lock, flags);
+
if (mrq->data) {
ret = tmio_mmc_start_data(host, mrq->data);
if (ret)
@@ -708,8 +729,8 @@ static void tmio_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
}
fail:
- host->mrq = NULL;
host->force_pio = false;
+ host->mrq = NULL;
mrq->cmd->error = ret;
mmc_request_done(mmc, mrq);
}
@@ -723,6 +744,29 @@ fail:
static void tmio_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
{
struct tmio_mmc_host *host = mmc_priv(mmc);
+ unsigned long flags;
+
+ spin_lock_irqsave(&host->lock, flags);
+ if (host->mrq) {
+ if (IS_ERR(host->mrq)) {
+ dev_dbg(&host->pdev->dev,
+ "%s.%d: concurrent .set_ios(), clk %u, mode %u\n",
+ current->comm, task_pid_nr(current),
+ ios->clock, ios->power_mode);
+ host->mrq = ERR_PTR(-EINTR);
+ } else {
+ dev_dbg(&host->pdev->dev,
+ "%s.%d: CMD%u active since %lu, now %lu!\n",
+ current->comm, task_pid_nr(current),
+ host->mrq->cmd->opcode, host->last_req_ts, jiffies);
+ }
+ spin_unlock_irqrestore(&host->lock, flags);
+ return;
+ }
+
+ host->mrq = ERR_PTR(-EBUSY);
+
+ spin_unlock_irqrestore(&host->lock, flags);
if (ios->clock)
tmio_mmc_set_clock(host, ios->clock);
@@ -753,6 +797,12 @@ static void tmio_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
/* Let things settle. delay taken from winCE driver */
udelay(140);
+ if (PTR_ERR(host->mrq) == -EINTR)
+ dev_dbg(&host->pdev->dev,
+ "%s.%d: IOS interrupted: clk %u, mode %u",
+ current->comm, task_pid_nr(current),
+ ios->clock, ios->power_mode);
+ host->mrq = NULL;
}
static int tmio_mmc_get_ro(struct mmc_host *mmc)
--
1.7.2.5
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