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authorDavid Brownell <david-b@pacbell.net>2008-07-24 00:30:33 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-24 13:47:33 -0400
commit5ad31a575157147b43fa84ef1e21471661653878 (patch)
treec4a42d45957362aa8391938ae3e11496321c19d8 /include/linux/rtc.h
parent53f1b1433da7eac2607a4a0898a221a4485fd732 (diff)
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 <dbrownell@users.sourceforge.net> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Jonathan Corbet <corbet@lwn.net> Acked-by: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/rtc.h')
-rw-r--r--include/linux/rtc.h17
1 files changed, 17 insertions, 0 deletions
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);
115 115
116extern struct class *rtc_class; 116extern struct class *rtc_class;
117 117
118/*
119 * For these RTC methods the device parameter is the physical device
120 * on whatever bus holds the hardware (I2C, Platform, SPI, etc), which
121 * was passed to rtc_device_register(). Its driver_data normally holds
122 * device state, including the rtc_device pointer for the RTC.
123 *
124 * Most of these methods are called with rtc_device.ops_lock held,
125 * through the rtc_*(struct rtc_device *, ...) calls.
126 *
127 * The (current) exceptions are mostly filesystem hooks:
128 * - the proc() hook for procfs
129 * - non-ioctl() chardev hooks: open(), release(), read_callback()
130 * - periodic irq calls: irq_set_state(), irq_set_freq()
131 *
132 * REVISIT those periodic irq calls *do* have ops_lock when they're
133 * issued through ioctl() ...
134 */
118struct rtc_class_ops { 135struct rtc_class_ops {
119 int (*open)(struct device *); 136 int (*open)(struct device *);
120 void (*release)(struct device *); 137 void (*release)(struct device *);