Merge tag 'printk-for-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

Pull printk updates from Petr Mladek:

 - Allow creaing nbcon console drivers with an unsafe write_atomic()
   callback that can only be called by the final nbcon_atomic_flush_unsafe().
   Otherwise, the driver would rely on the kthread.

   It is going to be used as the-best-effort approach for an
   experimental nbcon netconsole driver, see

     https://lore.kernel.org/r/20251121-nbcon-v1-2-503d17b2b4af@debian.org

   Note that a safe .write_atomic() callback is supposed to work in NMI
   context. But some networking drivers are not safe even in IRQ
   context:

     https://lore.kernel.org/r/oc46gdpmmlly5o44obvmoatfqo5bhpgv7pabpvb6sjuqioymcg@gjsma3ghoz35

   In an ideal world, all networking drivers would be fixed first and
   the atomic flush would be blocked only in NMI context. But it brings
   the question how reliable networking drivers are when the system is
   in a bad state. They might block flushing more reliable serial
   consoles which are more suitable for serious debugging anyway.

 - Allow to use the last 4 bytes of the printk ring buffer.

 - Prevent queuing IRQ work and block printk kthreads when consoles are
   suspended. Otherwise, they create non-necessary churn or even block
   the suspend.

 - Release console_lock() between each record in the kthread used for
   legacy consoles on RT. It might significantly speed up the boot.

 - Release nbcon context between each record in the atomic flush. It
   prevents stalls of the related printk kthread after it has lost the
   ownership in the middle of a record

 - Add support for NBCON consoles into KDB

 - Add %ptsP modifier for printing struct timespec64 and use it where
   possible

 - Misc code clean up

* tag 'printk-for-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: (48 commits)
  printk: Use console_is_usable on console_unblank
  arch: um: kmsg_dump: Use console_is_usable
  drivers: serial: kgdboc: Drop checks for CON_ENABLED and CON_BOOT
  lib/vsprintf: Unify FORMAT_STATE_NUM handlers
  printk: Avoid irq_work for printk_deferred() on suspend
  printk: Avoid scheduling irq_work on suspend
  printk: Allow printk_trigger_flush() to flush all types
  tracing: Switch to use %ptSp
  scsi: snic: Switch to use %ptSp
  scsi: fnic: Switch to use %ptSp
  s390/dasd: Switch to use %ptSp
  ptp: ocp: Switch to use %ptSp
  pps: Switch to use %ptSp
  PCI: epf-test: Switch to use %ptSp
  net: dsa: sja1105: Switch to use %ptSp
  mmc: mmc_test: Switch to use %ptSp
  media: av7110: Switch to use %ptSp
  ipmi: Switch to use %ptSp
  igb: Switch to use %ptSp
  e1000e: Switch to use %ptSp
  ...

2 files changed, 54 insertions, 30 deletions

diff --git a/lib/tests/printf_kunit.c b/lib/tests/printf_kunit.c
index bc54cca2d7a6..7617e5b8b02c 100644
--- a/lib/tests/printf_kunit.c
+++ b/lib/tests/printf_kunit.c
@@ -504,6 +504,7 @@ time_and_date(struct kunit *kunittest)
 	};
 	/* 2019-01-04T15:32:23 */
 	time64_t t = 1546615943;
+	struct timespec64 ts = { .tv_sec = t, .tv_nsec = 11235813 };
 
 	test("(%pt?)", "%pt", &tm);
 	test("2018-11-26T05:35:43", "%ptR", &tm);
@@ -522,6 +523,9 @@ time_and_date(struct kunit *kunittest)
 	test("0119-00-04 15:32:23", "%ptTsr", &t);
 	test("15:32:23|2019-01-04", "%ptTts|%ptTds", &t, &t);
 	test("15:32:23|0119-00-04", "%ptTtrs|%ptTdrs", &t, &t);
+
+	test("2019-01-04T15:32:23.011235813", "%ptS", &ts);
+	test("1546615943.011235813", "%ptSp", &ts);
 }
 
 static void
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index eb0cb11d0d12..a3790c43a0ab 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -582,17 +582,18 @@ char *number(char *buf, char *end, unsigned long long num,
 	return buf;
 }
 
+#define special_hex_spec(size)					\
+(struct printf_spec) {						\
+	.field_width = 2 + 2 * (size),		/* 0x + hex */	\
+	.flags = SPECIAL | SMALL | ZEROPAD,			\
+	.base = 16,						\
+	.precision = -1,					\
+}
+
 static noinline_for_stack
 char *special_hex_number(char *buf, char *end, unsigned long long num, int size)
 {
-	struct printf_spec spec;
-
-	spec.field_width = 2 + 2 * size;	/* 0x + hex */
-	spec.flags = SPECIAL | SMALL | ZEROPAD;
-	spec.base = 16;
-	spec.precision = -1;
-
-	return number(buf, end, num, spec);
+	return number(buf, end, num, special_hex_spec(size));
 }
 
 static void move_right(char *buf, char *end, unsigned len, unsigned spaces)
@@ -1164,18 +1165,11 @@ char *range_string(char *buf, char *end, const struct range *range,
 	char sym[sizeof("[range 0x0123456789abcdef-0x0123456789abcdef]")];
 	char *p = sym, *pend = sym + sizeof(sym);
 
-	struct printf_spec range_spec = {
-		.field_width = 2 + 2 * sizeof(range->start), /* 0x + 2 * 8 */
-		.flags = SPECIAL | SMALL | ZEROPAD,
-		.base = 16,
-		.precision = -1,
-	};
-
 	if (check_pointer(&buf, end, range, spec))
 		return buf;
 
 	p = string_nocheck(p, pend, "[range ", default_str_spec);
-	p = hex_range(p, pend, range->start, range->end, range_spec);
+	p = hex_range(p, pend, range->start, range->end, special_hex_spec(sizeof(range->start)));
 	*p++ = ']';
 	*p = '\0';
 
@@ -1928,9 +1922,6 @@ char *rtc_str(char *buf, char *end, const struct rtc_time *tm,
 	bool found = true;
 	int count = 2;
 
-	if (check_pointer(&buf, end, tm, spec))
-		return buf;
-
 	switch (fmt[count]) {
 	case 'd':
 		have_t = false;
@@ -1993,12 +1984,39 @@ char *time64_str(char *buf, char *end, const time64_t time,
 }
 
 static noinline_for_stack
+char *timespec64_str(char *buf, char *end, const struct timespec64 *ts,
+		     struct printf_spec spec, const char *fmt)
+{
+	static const struct printf_spec default_dec09_spec = {
+		.base = 10,
+		.field_width = 9,
+		.precision = -1,
+		.flags = ZEROPAD,
+	};
+
+	if (fmt[2] == 'p')
+		buf = number(buf, end, ts->tv_sec, default_dec_spec);
+	else
+		buf = time64_str(buf, end, ts->tv_sec, spec, fmt);
+	if (buf < end)
+		*buf = '.';
+	buf++;
+
+	return number(buf, end, ts->tv_nsec, default_dec09_spec);
+}
+
+static noinline_for_stack
 char *time_and_date(char *buf, char *end, void *ptr, struct printf_spec spec,
 		    const char *fmt)
 {
+	if (check_pointer(&buf, end, ptr, spec))
+		return buf;
+
 	switch (fmt[1]) {
 	case 'R':
 		return rtc_str(buf, end, (const struct rtc_time *)ptr, spec, fmt);
+	case 'S':
+		return timespec64_str(buf, end, (const struct timespec64 *)ptr, spec, fmt);
 	case 'T':
 		return time64_str(buf, end, *(const time64_t *)ptr, spec, fmt);
 	default:
@@ -2462,9 +2480,11 @@ early_param("no_hash_pointers", no_hash_pointers_enable);
  * - 'd[234]' For a dentry name (optionally 2-4 last components)
  * - 'D[234]' Same as 'd' but for a struct file
  * - 'g' For block_device name (gendisk + partition number)
- * - 't[RT][dt][r][s]' For time and date as represented by:
+ * - 't[RST][dt][r][s]' For time and date as represented by:
  *      R    struct rtc_time
+ *      S    struct timespec64
  *      T    time64_t
+ * - 'tSp' For time represented by struct timespec64 printed as <seconds>.<nanoseconds>
  * - 'C' For a clock, it prints the name (Common Clock Framework) or address
  *       (legacy clock framework) of the clock
  * - 'G' For flags to be printed as a collection of symbolic strings that would
@@ -2883,10 +2903,11 @@ int vsnprintf(char *buf, size_t size, const char *fmt_str, va_list args)
 
 		case FORMAT_STATE_NUM: {
 			unsigned long long num;
-			if (fmt.size <= sizeof(int))
-				num = convert_num_spec(va_arg(args, int), fmt.size, spec);
-			else
+
+			if (fmt.size > sizeof(int))
 				num = va_arg(args, long long);
+			else
+				num = convert_num_spec(va_arg(args, int), fmt.size, spec);
 			str = number(str, end, num, spec);
 			continue;
 		}
@@ -3054,8 +3075,8 @@ EXPORT_SYMBOL(scnprintf);
  * @fmt: The format string to use
  * @args: Arguments for the format string
  *
- * The function returns the number of characters written
- * into @buf. Use vsnprintf() or vscnprintf() in order to avoid
+ * The return value is the number of characters written into @buf not including
+ * the trailing '\0'. Use vsnprintf() or vscnprintf() in order to avoid
  * buffer overflows.
  *
  * If you're not already dealing with a va_list consider using sprintf().
@@ -3074,8 +3095,8 @@ EXPORT_SYMBOL(vsprintf);
  * @fmt: The format string to use
  * @...: Arguments for the format string
  *
- * The function returns the number of characters written
- * into @buf. Use snprintf() or scnprintf() in order to avoid
+ * The return value is the number of characters written into @buf not including
+ * the trailing '\0'. Use snprintf() or scnprintf() in order to avoid
  * buffer overflows.
  *
  * See the vsnprintf() documentation for format string extensions over C99.
@@ -3394,11 +3415,10 @@ int bstr_printf(char *buf, size_t size, const char *fmt_str, const u32 *bin_buf)
 			goto out;
 
 		case FORMAT_STATE_NUM:
-			if (fmt.size > sizeof(int)) {
+			if (fmt.size > sizeof(int))
 				num = get_arg(long long);
-			} else {
+			else
 				num = convert_num_spec(get_arg(int), fmt.size, spec);
-			}
 			str = number(str, end, num, spec);
 			continue;
 		}