Many parts of DPDK will fail with divide by zero and
other errors if the initialization logic ever TSC hz was ever
determined to be zero. This might happen on a broken get_tsc_freq_arch()
or bad emulation in QEMU.
If TSC hz is zero, log the error and propagate back to
fail rte_eal_init().
This fix doesn't need to go to stable since it is a purely
theoretical problem; we aren't getting divide by zero reports
from users.
Also, clarify that DPDK TSC is stable and the same for all lcore's.
The comment in rte_cycles.h implied that it could be different per lcore.
Fixes: 040cf8a41187 ("eal: deduplicate timer functions")
Signed-off-by: Stephen Hemminger <[email protected]>
Acked-by: Bruce Richardson <[email protected]>
---
v3 - rename set_tsc_freq to init_tsc_freq
lib/eal/common/eal_common_timer.c | 19 +++++++++++++++----
lib/eal/common/eal_private.h | 2 +-
lib/eal/freebsd/eal_timer.c | 3 +--
lib/eal/include/generic/rte_cycles.h | 2 +-
lib/eal/linux/eal_timer.c | 3 +--
lib/eal/windows/eal_timer.c | 3 +--
6 files changed, 20 insertions(+), 12 deletions(-)
diff --git a/lib/eal/common/eal_common_timer.c
b/lib/eal/common/eal_common_timer.c
index bbf8b8b11b..67ede70c62 100644
--- a/lib/eal/common/eal_common_timer.c
+++ b/lib/eal/common/eal_common_timer.c
@@ -52,8 +52,8 @@ estimate_tsc_freq(void)
return RTE_ALIGN_MUL_NEAR(rte_rdtsc() - start, CYC_PER_10MHZ);
}
-void
-set_tsc_freq(void)
+int
+init_tsc_freq(void)
{
struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
uint64_t freq;
@@ -65,18 +65,29 @@ set_tsc_freq(void)
* systems where arch-specific frequency detection is not
* available.
*/
+ if (mcfg->tsc_hz == 0) {
+ EAL_LOG(ERR, "Primary process TSC frequency is zero");
+ return -1;
+ }
+
eal_tsc_resolution_hz = mcfg->tsc_hz;
- return;
+ return 0;
}
freq = get_tsc_freq_arch();
freq = get_tsc_freq(freq);
- if (!freq)
+ if (freq == 0) {
freq = estimate_tsc_freq();
+ if (freq == 0) {
+ EAL_LOG(ERR, "TSC frequency is too slow");
+ return -1;
+ }
+ }
EAL_LOG(DEBUG, "TSC frequency is ~%" PRIu64 " KHz", freq / 1000);
eal_tsc_resolution_hz = freq;
mcfg->tsc_hz = freq;
+ return 0;
}
RTE_EXPORT_SYMBOL(rte_delay_us_callback_register)
diff --git a/lib/eal/common/eal_private.h b/lib/eal/common/eal_private.h
index 6340bab8be..7da3783c9e 100644
--- a/lib/eal/common/eal_private.h
+++ b/lib/eal/common/eal_private.h
@@ -409,7 +409,7 @@ int eal_cpu_detected(unsigned lcore_id);
*
* This function is private to the EAL.
*/
-void set_tsc_freq(void);
+int init_tsc_freq(void);
/**
* Get precise TSC frequency from system
diff --git a/lib/eal/freebsd/eal_timer.c b/lib/eal/freebsd/eal_timer.c
index d21ffa2694..b966c30258 100644
--- a/lib/eal/freebsd/eal_timer.c
+++ b/lib/eal/freebsd/eal_timer.c
@@ -65,6 +65,5 @@ get_tsc_freq(uint64_t arch_hz)
int
rte_eal_timer_init(void)
{
- set_tsc_freq();
- return 0;
+ return init_tsc_freq();
}
diff --git a/lib/eal/include/generic/rte_cycles.h
b/lib/eal/include/generic/rte_cycles.h
index 7cfd51f0eb..f8e1cde332 100644
--- a/lib/eal/include/generic/rte_cycles.h
+++ b/lib/eal/include/generic/rte_cycles.h
@@ -34,7 +34,7 @@ extern enum timer_source eal_timer_source;
* Get the measured frequency of the RDTSC counter
*
* @return
- * The TSC frequency for this lcore
+ * The TSC frequency for all lcores, always non-zero
*/
uint64_t
rte_get_tsc_hz(void);
diff --git a/lib/eal/linux/eal_timer.c b/lib/eal/linux/eal_timer.c
index 39f975b6b9..c425ea4ed8 100644
--- a/lib/eal/linux/eal_timer.c
+++ b/lib/eal/linux/eal_timer.c
@@ -99,6 +99,5 @@ rte_eal_timer_init(void)
eal_timer_source = EAL_TIMER_TSC;
- set_tsc_freq();
- return 0;
+ return init_tsc_freq();
}
diff --git a/lib/eal/windows/eal_timer.c b/lib/eal/windows/eal_timer.c
index 33cbac6a03..1e381ad673 100644
--- a/lib/eal/windows/eal_timer.c
+++ b/lib/eal/windows/eal_timer.c
@@ -94,6 +94,5 @@ get_tsc_freq(uint64_t arch_hz)
int
rte_eal_timer_init(void)
{
- set_tsc_freq();
- return 0;
+ return init_tsc_freq();
}
--
2.53.0
