drivers/rtc/rtc-r9701.c: fix crash in r9701_remove()
If probing the RTC didn't succeed due to failed RTC register access, the RTC device will be unregistered. Then, when removing the module r9701_remove() causes a kernel crash while trying to unregister a not registered RTC device. Fix this by doing RTC register access test before RTC device registration. Signed-off-by: Anatolij Gustschin <agust@denx.de> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -125,6 +125,13 @@ static int __devinit r9701_probe(struct spi_device *spi)
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unsigned char tmp;
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int res;
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tmp = R100CNT;
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res = read_regs(&spi->dev, &tmp, 1);
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if (res || tmp != 0x20) {
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dev_err(&spi->dev, "cannot read RTC register\n");
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return -ENODEV;
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}
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rtc = rtc_device_register("r9701",
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&spi->dev, &r9701_rtc_ops, THIS_MODULE);
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if (IS_ERR(rtc))
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@ -132,13 +139,6 @@ static int __devinit r9701_probe(struct spi_device *spi)
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dev_set_drvdata(&spi->dev, rtc);
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tmp = R100CNT;
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res = read_regs(&spi->dev, &tmp, 1);
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if (res || tmp != 0x20) {
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rtc_device_unregister(rtc);
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return res;
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}
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return 0;
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}
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