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utils: Don't lose log level when silencing kmsg

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Once we disable kmsg logging to the console, the kernel will set the
console log level to the minimum log level (i.e. only logging kernel
panics). However the unintended side effect is that our own kmsg-reader
will start filtering out all kernel log messages, since we also respect
the kernel's console log level.

This change make it so that we keep using the original console log level
whenever we disable the kernel's output. This lets us keep forwarding
the kernel's kmsg output
This commit is contained in:
Adrian Vovk 2025-05-09 14:44:24 -04:00
parent 4876cfa147
commit 2446472f9a
No known key found for this signature in database
GPG key ID: 90A7B546533E15FB
1 changed files with 47 additions and 32 deletions
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79
src/libply/ply-utils.c
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@ -89,6 +89,10 @@ static int overridden_device_scale = 0;
static char kernel_command_line[PLY_MAX_COMMAND_LINE_SIZE];
static bool kernel_command_line_is_set;
static int cached_current_log_level = 0;
static int cached_default_log_level = 0;
static double log_level_update_time = 0.0;
bool
ply_open_unidirectional_pipe (int *sender_fd,
int *receiver_fd)
@ -673,20 +677,6 @@ ply_create_file_link (const char *source,
return true;
}
void
ply_show_new_kernel_messages (bool should_show)
{
int type;
if (should_show)
type = PLY_ENABLE_CONSOLE_PRINTK;
else
type = PLY_DISABLE_CONSOLE_PRINTK;
if (klogctl (type, NULL, 0) < 0)
ply_trace ("could not toggle printk visibility: %m");
}
ply_daemon_handle_t *
ply_create_daemon (void)
{
@ -1118,26 +1108,14 @@ int ply_guess_device_scale (uint32_t width,
return get_device_scale (width, height, 0, 0, true);
}
void
ply_get_kmsg_log_levels (int *current_log_level,
int *default_log_level)
static void
ply_get_kmsg_log_levels_uncached (int *current_log_level,
int *default_log_level)
{
static double last_update_time = 0;
static int cached_current_log_level = 0;
static int cached_default_log_level = 0;
char log_levels[4096] = "";
double current_time;
char *field, *fields;
int fd;
current_time = ply_get_timestamp ();
if ((current_time - last_update_time) < 1.0) {
*current_log_level = cached_current_log_level;
*default_log_level = cached_default_log_level;
return;
}
ply_trace ("opening /proc/sys/kernel/printk");
fd = open ("/proc/sys/kernel/printk", O_RDONLY);
@ -1171,11 +1149,48 @@ ply_get_kmsg_log_levels (int *current_log_level,
}
*default_log_level = atoi (field);
}
cached_current_log_level = *current_log_level;
cached_default_log_level = *default_log_level;
void
ply_get_kmsg_log_levels (int *current_log_level,
int *default_log_level)
{
double current_time;
bool no_cache;
bool cache_expired;
last_update_time = current_time;
no_cache = cached_current_log_level == 0 || cached_default_log_level == 0;
current_time = ply_get_timestamp ();
cache_expired = log_level_update_time > 0.0 && (current_time - log_level_update_time) >= 1.0;
if (no_cache || cache_expired) {
ply_get_kmsg_log_levels_uncached (&cached_current_log_level, &cached_default_log_level);
log_level_update_time = current_time;
}
*current_log_level = cached_current_log_level;
*default_log_level = cached_default_log_level;
}
void
ply_show_new_kernel_messages (bool should_show)
{
int type;
if (should_show) {
type = PLY_ENABLE_CONSOLE_PRINTK;
cached_current_log_level = cached_default_log_level = 0;
log_level_update_time = 0.0;
} else {
type = PLY_DISABLE_CONSOLE_PRINTK;
ply_get_kmsg_log_levels_uncached (&cached_current_log_level, &cached_default_log_level);
log_level_update_time = -1.0; /* Disable expiration */
}
if (klogctl (type, NULL, 0) < 0)
ply_trace ("could not toggle printk visibility: %m");
}
static const char *