This patch implements a real-time safe rate-limited message printing
on kernel console similar to Linux's printk_ratelimited.
Signed-off-by: Wolfgang Grandegger <w...@denx.de>
---
include/rtdm/rtdm_driver.h | 31 +++++++++++++++++
ksrc/skins/rtdm/drvlib.c | 77 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 108 insertions(+), 0 deletions(-)
diff --git a/include/rtdm/rtdm_driver.h b/include/rtdm/rtdm_driver.h
index 85624ed..4267bd7 100644
--- a/include/rtdm/rtdm_driver.h
+++ b/include/rtdm/rtdm_driver.h
@@ -1241,6 +1241,37 @@ static inline void rtdm_mutex_destroy(rtdm_mutex_t
*mutex)
#define rtdm_printk(format, ...) printk(format, ##__VA_ARGS__)
+struct rtdm_ratelimit_state {
+ rtdm_lock_t lock; /* protect the state */
+ nanosecs_abs_t interval;
+ int burst;
+ int printed;
+ int missed;
+ nanosecs_abs_t begin;
+};
+
+int rtdm_ratelimit(struct rtdm_ratelimit_state *rs, const char *func);
+
+#define DEFINE_RTDM_RATELIMIT_STATE(name, interval_init, burst_init) \
+ struct rtdm_ratelimit_state name = { \
+ .lock = RTDM_LOCK_UNLOCKED, \
+ .interval = interval_init, \
+ .burst = burst_init, \
+ }
+
+/* We use the Linux defaults */
+#define DEF_RTDM_RATELIMIT_INTERVAL 5000000000LL
+#define DEF_RTDM_RATELIMIT_BURST 10
+
+#define rtdm_printk_ratelimited(fmt, ...) ({ \
+ static DEFINE_RTDM_RATELIMIT_STATE(_rs, \
+ DEF_RTDM_RATELIMIT_INTERVAL, \
+ DEF_RTDM_RATELIMIT_BURST); \
+ \
+ if (rtdm_ratelimit(&_rs, __func__)) \
+ printk(fmt, ##__VA_ARGS__); \
+})
+
#ifndef DOXYGEN_CPP /* Avoid static inline tags for RTDM in doxygen */
static inline void *rtdm_malloc(size_t size)
{
diff --git a/ksrc/skins/rtdm/drvlib.c b/ksrc/skins/rtdm/drvlib.c
index 8c86705..06fa772 100644
--- a/ksrc/skins/rtdm/drvlib.c
+++ b/ksrc/skins/rtdm/drvlib.c
@@ -2111,9 +2111,86 @@ int rtdm_munmap(rtdm_user_info_t *user_info, void *ptr,
size_t len)
EXPORT_SYMBOL_GPL(rtdm_munmap);
#endif /* CONFIG_XENO_OPT_PERVASIVE || DOXYGEN_CPP */
+/**
+ * @brief Enforces a rate limit
+ *
+ * This function enforces a rate limit: not more than @rs->burst callbacks
+ * in every @rs->interval.
+ *
+ * @param[in,out] rtdm_ratelimit_state data
+ * @param[in] name of calling function
+ *
+ * @return 0 means callback will be suppressed and 1 means go ahead and do it
+ *
+ * Environments:
+ *
+ * This service can be called from:
+ *
+ * - Kernel module initialization/cleanup code
+ * - Kernel-based task
+ * - User-space task (RT, non-RT)
+ *
+ * Rescheduling: possible.
+ */
+int rtdm_ratelimit(struct rtdm_ratelimit_state *rs, const char *func)
+{
+ rtdm_lockctx_t lock_ctx;
+ int ret;
+
+ if (!rs->interval)
+ return 1;
+
+ rtdm_lock_get_irqsave(&rs->lock, lock_ctx);
+
+ if (!rs->begin)
+ rs->begin = rtdm_clock_read();
+ if (rtdm_clock_read() >= rs->begin + rs->interval) {
+ if (rs->missed)
+ printk(KERN_WARNING "%s: %d callbacks suppressed\n",
+ func, rs->missed);
+ rs->begin = 0;
+ rs->printed = 0;
+ rs->missed = 0;
+ }
+ if (rs->burst && rs->burst > rs->printed) {
+ rs->printed++;
+ ret = 1;
+ } else {
+ rs->missed++;
+ ret = 0;
+ }
+ rtdm_lock_put_irqrestore(&rs->lock, lock_ctx);
+
+ return ret;
+}
+EXPORT_SYMBOL(rtdm_ratelimit);
+
#ifdef DOXYGEN_CPP /* Only used for doxygen doc generation */
/**
+ * Real-time safe rate-limited message printing on kernel console
+ *
+ * @param[in] format Format string (conforming standard @c printf())
+ * @param ... Arguments referred by @a format
+ *
+ * @return On success, this service returns the number of characters printed.
+ * Otherwise, a negative error code is returned.
+ *
+ * Environments:
+ *
+ * This service can be called from:
+ *
+ * - Kernel module initialization/cleanup code
+ * - Interrupt service routine (consider the overhead!)
+ * - Kernel-based task
+ * - User-space task (RT, non-RT)
+ *
+ * Rescheduling: never in real-time context, possible in non-real-time
+ * environments.
+ */
+void rtdm_printk_ratelimited(const char *format, ...);
+
+/**
* Real-time safe message printing on kernel console
*
* @param[in] format Format string (conforming standard @c printf())
--
1.7.4.1
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