From 5ad31a575157147b43fa84ef1e21471661653878 Mon Sep 17 00:00:00 2001 From: David Brownell Date: Wed, 23 Jul 2008 21:30:33 -0700 Subject: rtc: remove BKL for ioctl() Remove implicit use of BKL in ioctl() from the RTC framework. Instead, the rtc->ops_lock is used. That's the same lock that already protects the RTC operations when they're issued through the exported rtc_*() calls in drivers/rtc/interface.c ... making this a bugfix, not just a cleanup, since both ioctl calls and set_alarm() need to update IRQ enable flags and that implies a common lock (which RTC drivers as a rule do not provide on their own). A new comment at the declaration of "struct rtc_class_ops" summarizes current locking rules. It's not clear to me that the exceptions listed there should exist ... if not, those are pre-existing problems which can be fixed in a patch that doesn't relate to BKL removal. Signed-off-by: David Brownell Cc: Alan Cox Cc: Jonathan Corbet Acked-by: Alessandro Zummo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/rtc.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'include/linux/rtc.h') diff --git a/include/linux/rtc.h b/include/linux/rtc.h index f2d0d1527721..b01fe004cb5e 100644 --- a/include/linux/rtc.h +++ b/include/linux/rtc.h @@ -115,6 +115,23 @@ extern void rtc_time_to_tm(unsigned long time, struct rtc_time *tm); extern struct class *rtc_class; +/* + * For these RTC methods the device parameter is the physical device + * on whatever bus holds the hardware (I2C, Platform, SPI, etc), which + * was passed to rtc_device_register(). Its driver_data normally holds + * device state, including the rtc_device pointer for the RTC. + * + * Most of these methods are called with rtc_device.ops_lock held, + * through the rtc_*(struct rtc_device *, ...) calls. + * + * The (current) exceptions are mostly filesystem hooks: + * - the proc() hook for procfs + * - non-ioctl() chardev hooks: open(), release(), read_callback() + * - periodic irq calls: irq_set_state(), irq_set_freq() + * + * REVISIT those periodic irq calls *do* have ops_lock when they're + * issued through ioctl() ... + */ struct rtc_class_ops { int (*open)(struct device *); void (*release)(struct device *); -- cgit