AcoSail/kernel_optimize_test
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mmc: protect the tmio_mmc driver against a theoretical race

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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@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Guennadi Liakhovetski 2011-04-21 07:20:16 +00:00 committed by Chris Ball
parent faca6648e6
commit df3ef2d3c9
2 changed files with 57 additions and 6 deletions
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1
drivers/mmc/host/tmio_mmc.h
View File

@ -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

62
drivers/mmc/host/tmio_mmc_pio.c
View File

@ -244,8 +244,12 @@ 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);
@ -265,16 +269,19 @@ 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;
@ -282,13 +289,15 @@ 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);
}
@ -686,15 +695,27 @@ 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)
@ -709,8 +730,8 @@ 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);
}
@ -724,6 +745,29 @@ static void tmio_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
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);
@ -754,6 +798,12 @@ 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)