diff options
author | Stephen Warren <swarren@nvidia.com> | 2014-09-22 15:57:42 (GMT) |
---|---|---|
committer | Ulf Hansson <ulf.hansson@linaro.org> | 2014-09-23 07:01:36 (GMT) |
commit | d4d11449088ee9aca16fd1884b852b8b73a4bda1 (patch) | |
tree | ab75101a771c35d48949e95be487b1107474571b /drivers/mmc/core | |
parent | bb98d9d1d2e791f368295c9c09c9a03fe3ac0e62 (diff) | |
download | linux-d4d11449088ee9aca16fd1884b852b8b73a4bda1.tar.xz |
mmc: don't request CD IRQ until mmc_start_host()
As soon as the CD IRQ is requested, it can trigger, since it's an
externally controlled event. If it does, delayed_work host->detect will
be scheduled.
Many host controller probe()s are roughly structured as:
*_probe() {
host = sdhci_pltfm_init();
mmc_of_parse(host->mmc);
rc = sdhci_add_host(host);
if (rc) {
sdhci_pltfm_free();
return rc;
}
In 3.17, CD IRQs can are enabled quite early via *_probe() ->
mmc_of_parse() -> mmc_gpio_request_cd() -> mmc_gpiod_request_cd_irq().
Note that in linux-next, mmc_of_parse() calls mmc_gpio*d*_request_cd()
rather than mmc_gpio_request_cd(), and mmc_gpio*d*_request_cd() doesn't
call mmc_gpiod_request_cd_irq(). However, this issue still exists if
mmc_gpio_request_cd() is called directly before mmc_start_host().
sdhci_add_host() may fail part way through (e.g. due to deferred
probe for a vmmc regulator), and sdhci_pltfm_free() does nothing to
unrequest the CD IRQ nor cancel the delayed_work. sdhci_pltfm_free() is
coded to assume that if sdhci_add_host() failed, then the delayed_work
cannot (or should not) have been triggered.
This can lead to the following with CONFIG_DEBUG_OBJECTS_* enabled, when
kfree(host) is eventually called inside sdhci_pltfm_free():
WARNING: CPU: 2 PID: 6 at lib/debugobjects.c:263 debug_print_object+0x8c/0xb4()
ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x18
The object being complained about is host->detect.
There's no need to request the CD IRQ so early; mmc_start_host() already
requests it. For most SDHCI hosts at least, the typical call path that
does this is: *_probe() -> sdhci_add_host() -> mmc_add_host() ->
mmc_start_host(). Therefore, remove the call to mmc_gpiod_request_cd_irq()
from mmc_gpio_request_cd(). This also matches mmc_gpio*d*_request_cd(),
which already doesn't call mmc_gpiod_request_cd_irq().
However, some host controller drivers call mmc_gpio_request_cd() after
mmc_start_host() has already been called, and assume that this will also
call mmc_gpiod_request_cd_irq(). Update those drivers to explicitly call
mmc_gpiod_request_cd_irq() themselves. Ideally, these drivers should be
modified to move their call to mmc_gpio_request_cd() before their call
to mmc_add_host(). However that's too large a change for stable.
This solves the problem (eliminates the kernel error message above),
since it guarantees that the IRQ can't trigger before mmc_start_host()
is called.
The critical point here is that once sdhci_add_host() calls
mmc_add_host() -> mmc_start_host(), sdhci_add_host() is coded not to
fail. In other words, if there's a chance that mmc_start_host() may have
been called, and CD IRQs triggered, and the delayed_work scheduled,
sdhci_add_host() won't fail, and so cleanup is no longer via
sdhci_pltfm_free() (which doesn't free the IRQ or cancel the work queue)
but instead must be via sdhci_remove_host(), which calls mmc_remove_host()
-> mmc_stop_host(), which does free the IRQ and cancel the work queue.
CC: Russell King <linux@arm.linux.org.uk>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: <stable@vger.kernel.org> # v3.15+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc/core')
-rw-r--r-- | drivers/mmc/core/slot-gpio.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/drivers/mmc/core/slot-gpio.c b/drivers/mmc/core/slot-gpio.c index e3fce44..3af30e9 100644 --- a/drivers/mmc/core/slot-gpio.c +++ b/drivers/mmc/core/slot-gpio.c @@ -221,8 +221,6 @@ int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio, ctx->override_cd_active_level = true; ctx->cd_gpio = gpio_to_desc(gpio); - mmc_gpiod_request_cd_irq(host); - return 0; } EXPORT_SYMBOL(mmc_gpio_request_cd); |