summaryrefslogtreecommitdiffstats
path: root/kernel/printk
diff options
context:
space:
mode:
authorPetr Mladek <pmladek@suse.com>2020-06-01 10:15:16 +0200
committerPetr Mladek <pmladek@suse.com>2020-06-01 10:15:16 +0200
commitd053cf0d771f6547cb0537759a9af63cf402908d (patch)
treedf61806e45c6cf7e9cdd0b271f959f0962f8623e /kernel/printk
parent6a0af9fc8ccef5304ef88dc7e27362732e047076 (diff)
parenteb012d125a2419786f5bcaaf8a901babc7b6e3d7 (diff)
downloadlinux-d053cf0d771f6547cb0537759a9af63cf402908d.tar.gz
linux-d053cf0d771f6547cb0537759a9af63cf402908d.tar.bz2
linux-d053cf0d771f6547cb0537759a9af63cf402908d.zip
Merge branch 'for-5.8' into for-linus
Diffstat (limited to 'kernel/printk')
-rw-r--r--kernel/printk/internal.h5
-rw-r--r--kernel/printk/printk.c100
-rw-r--r--kernel/printk/printk_safe.c11
3 files changed, 84 insertions, 32 deletions
diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index c8e6ab689d42..b2b0f526f249 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -23,6 +23,9 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args);
void __printk_safe_enter(void);
void __printk_safe_exit(void);
+void printk_safe_init(void);
+bool printk_percpu_data_ready(void);
+
#define printk_safe_enter_irqsave(flags) \
do { \
local_irq_save(flags); \
@@ -64,4 +67,6 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args) { return 0; }
#define printk_safe_enter_irq() local_irq_disable()
#define printk_safe_exit_irq() local_irq_enable()
+static inline void printk_safe_init(void) { }
+static inline bool printk_percpu_data_ready(void) { return false; }
#endif /* CONFIG_PRINTK */
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index c59d9a1567ad..2bafd5ce4057 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -461,6 +461,18 @@ static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
static char *log_buf = __log_buf;
static u32 log_buf_len = __LOG_BUF_LEN;
+/*
+ * We cannot access per-CPU data (e.g. per-CPU flush irq_work) before
+ * per_cpu_areas are initialised. This variable is set to true when
+ * it's safe to access per-CPU data.
+ */
+static bool __printk_percpu_data_ready __read_mostly;
+
+bool printk_percpu_data_ready(void)
+{
+ return __printk_percpu_data_ready;
+}
+
/* Return log buffer address */
char *log_buf_addr_get(void)
{
@@ -963,6 +975,16 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
user->idx = log_next_idx;
user->seq = log_next_seq;
break;
+ case SEEK_CUR:
+ /*
+ * It isn't supported due to the record nature of this
+ * interface: _SET _DATA and _END point to very specific
+ * record positions, while _CUR would be more useful in case
+ * of a byte-based log. Because of that, return the default
+ * errno value for invalid seek operation.
+ */
+ ret = -ESPIPE;
+ break;
default:
ret = -EINVAL;
}
@@ -1147,12 +1169,28 @@ static void __init log_buf_add_cpu(void)
static inline void log_buf_add_cpu(void) {}
#endif /* CONFIG_SMP */
+static void __init set_percpu_data_ready(void)
+{
+ printk_safe_init();
+ /* Make sure we set this flag only after printk_safe() init is done */
+ barrier();
+ __printk_percpu_data_ready = true;
+}
+
void __init setup_log_buf(int early)
{
unsigned long flags;
char *new_log_buf;
unsigned int free;
+ /*
+ * Some archs call setup_log_buf() multiple times - first is very
+ * early, e.g. from setup_arch(), and second - when percpu_areas
+ * are initialised.
+ */
+ if (!early)
+ set_percpu_data_ready();
+
if (log_buf != __log_buf)
return;
@@ -1773,9 +1811,6 @@ static void call_console_drivers(const char *ext_text, size_t ext_len,
trace_console_rcuidle(text, len);
- if (!console_drivers)
- return;
-
for_each_console(con) {
if (exclusive_console && con != exclusive_console)
continue;
@@ -2169,6 +2204,9 @@ static int __init console_setup(char *str)
char *s, *options, *brl_options = NULL;
int idx;
+ if (str[0] == 0)
+ return 1;
+
if (_braille_console_setup(&str, &brl_options))
return 1;
@@ -2712,19 +2750,17 @@ void register_console(struct console *newcon)
struct console *bcon = NULL;
int err;
- if (console_drivers)
- for_each_console(bcon)
- if (WARN(bcon == newcon,
- "console '%s%d' already registered\n",
- bcon->name, bcon->index))
- return;
+ for_each_console(bcon) {
+ if (WARN(bcon == newcon, "console '%s%d' already registered\n",
+ bcon->name, bcon->index))
+ return;
+ }
/*
* before we register a new CON_BOOT console, make sure we don't
* already have a valid console
*/
- if (console_drivers && newcon->flags & CON_BOOT) {
- /* find the last or real console */
+ if (newcon->flags & CON_BOOT) {
for_each_console(bcon) {
if (!(bcon->flags & CON_BOOT)) {
pr_info("Too late to register bootconsole %s%d\n",
@@ -2847,7 +2883,7 @@ EXPORT_SYMBOL(register_console);
int unregister_console(struct console *console)
{
- struct console *a, *b;
+ struct console *con;
int res;
pr_info("%sconsole [%s%d] disabled\n",
@@ -2855,26 +2891,30 @@ int unregister_console(struct console *console)
console->name, console->index);
res = _braille_unregister_console(console);
- if (res)
+ if (res < 0)
return res;
+ if (res > 0)
+ return 0;
- res = 1;
+ res = -ENODEV;
console_lock();
if (console_drivers == console) {
console_drivers=console->next;
res = 0;
- } else if (console_drivers) {
- for (a=console_drivers->next, b=console_drivers ;
- a; b=a, a=b->next) {
- if (a == console) {
- b->next = a->next;
+ } else {
+ for_each_console(con) {
+ if (con->next == console) {
+ con->next = console->next;
res = 0;
break;
}
}
}
- if (!res && (console->flags & CON_EXTENDED))
+ if (res)
+ goto out_disable_unlock;
+
+ if (console->flags & CON_EXTENDED)
nr_ext_console_drivers--;
/*
@@ -2887,6 +2927,16 @@ int unregister_console(struct console *console)
console->flags &= ~CON_ENABLED;
console_unlock();
console_sysfs_notify();
+
+ if (console->exit)
+ res = console->exit(console);
+
+ return res;
+
+out_disable_unlock:
+ console->flags &= ~CON_ENABLED;
+ console_unlock();
+
return res;
}
EXPORT_SYMBOL(unregister_console);
@@ -3000,6 +3050,9 @@ static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
void wake_up_klogd(void)
{
+ if (!printk_percpu_data_ready())
+ return;
+
preempt_disable();
if (waitqueue_active(&log_wait)) {
this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
@@ -3010,6 +3063,9 @@ void wake_up_klogd(void)
void defer_console_output(void)
{
+ if (!printk_percpu_data_ready())
+ return;
+
preempt_disable();
__this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
@@ -3351,7 +3407,7 @@ out:
EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer);
/**
- * kmsg_dump_rewind_nolock - reset the interator (unlocked version)
+ * kmsg_dump_rewind_nolock - reset the iterator (unlocked version)
* @dumper: registered kmsg dumper
*
* Reset the dumper's iterator so that kmsg_dump_get_line() and
@@ -3369,7 +3425,7 @@ void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
}
/**
- * kmsg_dump_rewind - reset the interator
+ * kmsg_dump_rewind - reset the iterator
* @dumper: registered kmsg dumper
*
* Reset the dumper's iterator so that kmsg_dump_get_line() and
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index b4045e782743..d9a659a686f3 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -27,7 +27,6 @@
* There are situations when we want to make sure that all buffers
* were handled or when IRQs are blocked.
*/
-static int printk_safe_irq_ready __read_mostly;
#define SAFE_LOG_BUF_LEN ((1 << CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT) - \
sizeof(atomic_t) - \
@@ -51,7 +50,7 @@ static DEFINE_PER_CPU(struct printk_safe_seq_buf, nmi_print_seq);
/* Get flushed in a more safe context. */
static void queue_flush_work(struct printk_safe_seq_buf *s)
{
- if (printk_safe_irq_ready)
+ if (printk_percpu_data_ready())
irq_work_queue(&s->work);
}
@@ -402,14 +401,6 @@ void __init printk_safe_init(void)
#endif
}
- /*
- * In the highly unlikely event that a NMI were to trigger at
- * this moment. Make sure IRQ work is set up before this
- * variable is set.
- */
- barrier();
- printk_safe_irq_ready = 1;
-
/* Flush pending messages that did not have scheduled IRQ works. */
printk_safe_flush();
}