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| author | Stewart Smith <stewart@linux.vnet.ibm.com> | 2016-08-02 04:50:16 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2018-01-27 13:15:59 +0300 |
| commit | 5b8b58063029f02da573120ef4dc9079822e3cda (patch) | |
| tree | 1e253d31ee131d57812aa4c6df385b5248fea2ad /drivers/rtc | |
| parent | 77720c82915a8b7797e0041af95707d7485b4a40 (diff) | |
| download | linux-5b8b58063029f02da573120ef4dc9079822e3cda.tar.xz | |
rtc-opal: Fix handling of firmware error codes, prevent busy loops
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: 16b1d26e77b1 ("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>
Diffstat (limited to 'drivers/rtc')
| -rw-r--r-- | drivers/rtc/rtc-opal.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/rtc/rtc-opal.c b/drivers/rtc/rtc-opal.c index e2a946c0e667..304e891e35fc 100644 --- a/drivers/rtc/rtc-opal.c +++ b/drivers/rtc/rtc-opal.c @@ -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; |