[PATCH v2 3/7] xen/console: add build-time rate-limiting controls

[dmukhin@xxxxxxxx]

From: Denis Mukhin <dmukhin@xxxxxxxx> 

Introduce CONFIG_PRINTK_RATELIMIT_MS and CONFIG_PRINTK_RATELIMIT_BURST
for configuring rate-limiting policy at the compile time.

Use symbols for global rate-limiting initialization in the console driver.

Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
---
Changes since v1:
- new patch
---
 xen/drivers/char/Kconfig   | 25 +++++++++++++++++++++++++
 xen/drivers/char/console.c |  6 ++++--
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/xen/drivers/char/Kconfig b/xen/drivers/char/Kconfig
index 8e49a52c735b..98b117762a0c 100644
--- a/xen/drivers/char/Kconfig
+++ b/xen/drivers/char/Kconfig
@@ -103,3 +103,28 @@ config XHCI
          Enabling this option makes Xen use extra ~230KiB memory, even if XHCI 
UART
          is not selected.
          If you have an x86 based system with USB3, say Y.
+
+config PRINTK_RATELIMIT_MS
+       int "printk rate-limiting time window (milliseconds)"
+       default 5000
+       help
+         Specifies the time window, in milliseconds, for rate-limited printk
+         messages. No more than `CONFIG_PRINTK_RATELIMIT_BURST` messages will 
be
+         printed within this window.
+
+         Setting this value to 0 disables rate-limiting entirely.
+
+         Rate-limited messages are those controlled by the `loglvl` and
+         `guest_loglvl` command-line parameters.
+
+config PRINTK_RATELIMIT_BURST
+       int "printk rate-limited message burst size"
+       default 10
+       help
+         Defines the maximum number of rate-limited printk messages that may be
+         printed within each `CONFIG_PRINTK_RATELIMIT_MS` time window.
+
+         Setting this value to 0 disables rate-limiting entirely.
+
+         Rate-limited messages are those controlled by the `loglvl` and
+         `guest_loglvl` command-line parameters.
diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index c4c92e3efa39..ec87ecb3e5a0 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -1321,10 +1321,12 @@ static bool do_printk_ratelimit(unsigned int 
ratelimit_ms,
 }
 
 /* Minimum time in ms between messages */
-static const unsigned int printk_ratelimit_ms = 5 * 1000;
+static const unsigned int printk_ratelimit_ms =
+    CONFIG_PRINTK_RATELIMIT_MS;
 
 /* Number of messages we send before ratelimiting */
-static const unsigned int printk_ratelimit_burst = 10;
+static const unsigned int printk_ratelimit_burst =
+    CONFIG_PRINTK_RATELIMIT_BURST;
 
 bool printk_ratelimit(void)
 {
-- 
2.52.0