From: Daniel Stodden <daniel.stodden@citrix.com>
Date: Mon, 23 May 2011 02:23:46 +0000 (-0700)
Subject: MAR-125: Add driver log rate limits.
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=463c0fc1ed60c7b942093f51ceefda8c352ee4d1;p=people%2Fdstodden%2Fblktap.git

MAR-125: Add driver log rate limits.

Allocates one td-loglimit instance per driver instance. Present burst
size is 16 messages, over an interval of 90 seconds. To be shared by
both driver code and the VBD.

Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
---

diff --git a/drivers/tapdisk-driver.c b/drivers/tapdisk-driver.c
index 737bc2e..e9477b1 100644
--- a/drivers/tapdisk-driver.c
+++ b/drivers/tapdisk-driver.c
@@ -34,6 +34,38 @@
 #include "tapdisk-disktype.h"
 #include "tapdisk-stats.h"
 
+static void
+tapdisk_driver_log_flush(td_driver_t *driver, const char *__caller)
+{
+	td_loglimit_t *rl = &driver->loglimit;
+
+	if (rl->dropped) {
+		tlog_syslog(LOG_WARNING,
+			    "%s: %s: %d messages suppressed",
+			    driver->name, __caller, rl->dropped);
+		rl->dropped = 0;
+	}
+}
+
+int
+tapdisk_driver_log_pass(td_driver_t *driver, const char *__caller)
+{
+	td_loglimit_t *rl = &driver->loglimit;
+	int dropping = rl->dropped;
+
+	if (tapdisk_loglimit_pass(rl)) {
+		tapdisk_driver_log_flush(driver, __caller);
+		return 1;
+	}
+
+	if (!dropping)
+		tlog_syslog(LOG_WARNING,
+			    "%s: %s: too many errors, dropped.",
+			    driver->name, __caller);
+
+	return 0;
+}
+
 td_driver_t *
 tapdisk_driver_allocate(int type, const char *name, td_flag_t flags)
 {
@@ -63,6 +95,10 @@ tapdisk_driver_allocate(int type, const char *name, td_flag_t flags)
 	if (td_flag_test(flags, TD_OPEN_RDONLY))
 		td_flag_set(driver->state, TD_DRIVER_RDONLY);
 
+	tapdisk_loglimit_init(&driver->loglimit,
+			      16 /* msgs */,
+			      90 * 1000 /* ms */);
+
 	return driver;
 
 fail:
@@ -85,6 +121,8 @@ tapdisk_driver_free(td_driver_t *driver)
 		EPRINTF("freeing open driver %s (state 0x%08x)\n",
 			driver->name, driver->state);
 
+	tapdisk_driver_log_flush(driver, __func__);
+
 	free(driver->name);
 	free(driver->data);
 	free(driver);
diff --git a/drivers/tapdisk-driver.h b/drivers/tapdisk-driver.h
index f8464aa..f286bc9 100644
--- a/drivers/tapdisk-driver.h
+++ b/drivers/tapdisk-driver.h
@@ -31,6 +31,7 @@
 #include "tapdisk.h"
 #include "scheduler.h"
 #include "tapdisk-queue.h"
+#include "tapdisk-loglimit.h"
 
 #define TD_DRIVER_OPEN               0x0001
 #define TD_DRIVER_RDONLY             0x0002
@@ -49,6 +50,7 @@ struct td_driver_handle {
 	void                        *data;
 	const struct tap_disk       *ops;
 
+	td_loglimit_t                loglimit;
 	struct list_head             next;
 };
 
@@ -61,4 +63,6 @@ void tapdisk_driver_debug(td_driver_t *);
 
 void tapdisk_driver_stats(td_driver_t *, td_stats_t *);
 
+int tapdisk_driver_log_pass(td_driver_t *, const char *caller);
+
 #endif
diff --git a/drivers/tapdisk-log.h b/drivers/tapdisk-log.h
index eeac304..0afc899 100644
--- a/drivers/tapdisk-log.h
+++ b/drivers/tapdisk-log.h
@@ -60,4 +60,9 @@ void __tlog_error(const char *fmt, ...) __printf(1, 2);
 	__tlog_error("ERROR: errno %d at %s: " _f,	\
 		     _err, __func__, ##_a)
 
+#define tlog_drv_error(_drv, _err, _f, _a ...) do {	\
+	if (tapdisk_driver_log_pass(_drv, __func__))	\
+		tlog_error(_err, _f, ##_a);		\
+} while (0)
+
 #endif