rtc-opal: Fix handling of firmware error codes, prevent busy loops (5b8b5806) · Commits · 戴 / test

According to the OPAL docs: skiboot-5.2.5/doc/opal-api/opal-rtc-read-3.txt skiboot-5.2.5/doc/opal-api/opal-rtc-write-4.txt OPAL_HARDWARE may be returned from OPAL_RTC_READ or OPAL_RTC_WRITE and this indicates either a transient or permanent error. Prior to this patch, Linux was not dealing with OPAL_HARDWARE being a permanent error particularly well, in that you could end up in a busy loop. This was not too hard to trigger on an AMI BMC based OpenPOWER machine doing a continuous "ipmitool mc reset cold" to the BMC, the result of that being that we'd get stuck in an infinite loop in opal_get_rtc_time(). We now retry a few times before returning the error higher up the stack. Fixes: ("rtc/tpo: Driver to support rtc and wakeup on PowerNV platform") Cc: stable@vger.kernel.org # v3.19+ Signed-off-by:

Stewart Smith <stewart@linux.vnet.ibm.com> Signed-off-by:

Michael Ellerman <mpe@ellerman.id.au>

drivers/rtc/rtc-opal.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -58,6 +58,7 @@ static void tm_to_opal(struct rtc_time tm, u32 y_m_d, u64 *h_m_s_ms)
		static int opal_get_rtc_time(struct device dev, struct rtc_time tm)
		{
		long rc = OPAL_BUSY;
		int retries = 10;
		u32 y_m_d;
		u64 h_m_s_ms;
		__be32 __y_m_d;
		@@ -67,8 +68,11 @@ static int opal_get_rtc_time(struct device dev, struct rtc_time tm)
		rc = opal_rtc_read(&__y_m_d, &__h_m_s_ms);
		if (rc == OPAL_BUSY_EVENT)
		opal_poll_events(NULL);
		else
		else if (retries-- && (rc == OPAL_HARDWARE
		\|\| rc == OPAL_INTERNAL_ERROR))
		msleep(10);
		else if (rc != OPAL_BUSY && rc != OPAL_BUSY_EVENT)
		break;
		}

		if (rc != OPAL_SUCCESS)
		@@ -84,6 +88,7 @@ static int opal_get_rtc_time(struct device dev, struct rtc_time tm)
		static int opal_set_rtc_time(struct device dev, struct rtc_time tm)
		{
		long rc = OPAL_BUSY;
		int retries = 10;
		u32 y_m_d = 0;
		u64 h_m_s_ms = 0;

		@@ -92,8 +97,11 @@ static int opal_set_rtc_time(struct device dev, struct rtc_time tm)
		rc = opal_rtc_write(y_m_d, h_m_s_ms);
		if (rc == OPAL_BUSY_EVENT)
		opal_poll_events(NULL);
		else
		else if (retries-- && (rc == OPAL_HARDWARE
		\|\| rc == OPAL_INTERNAL_ERROR))
		msleep(10);
		else if (rc != OPAL_BUSY && rc != OPAL_BUSY_EVENT)
		break;
		}

		return rc == OPAL_SUCCESS ? 0 : -EIO;

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