Merge tag 'printk-for-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Merge commit. Changes below are compared with the first parent: 916a7596.
Changes
16 files changed · +502 −340
| File | Status | Add | Del | Content |
|---|---|---|---|---|
| Documentation/core-api/printk-formats.rst | modified | +26 | −2 | View file |
| MAINTAINERS | modified | +4 | −4 | View file |
| arch/powerpc/kernel/nvram_64.c | modified | +5 | −3 | View file |
| arch/powerpc/xmon/xmon.c | modified | +3 | −3 | View file |
| arch/um/kernel/kmsg_dump.c | modified | +12 | −1 | View file |
| drivers/hv/vmbus_drv.c | modified | +3 | −1 | View file |
| drivers/mtd/mtdoops.c | modified | +15 | −2 | View file |
| fs/pstore/platform.c | modified | +4 | −1 | View file |
| include/linux/kmsg_dump.h | modified | +17 | −30 | View file |
| kernel/debug/kdb/kdb_main.c | modified | +5 | −5 | View file |
| kernel/printk/internal.h | modified | +1 | −6 | View file |
| kernel/printk/printk.c | modified | +240 | −238 | View file |
| kernel/printk/printk_safe.c | modified | +11 | −19 | View file |
| lib/test_printf.c | modified | +80 | −10 | View file |
| lib/vsprintf.c | modified | +69 | −9 | View file |
| mm/slub.c | modified | +7 | −6 | View file |
Only the first 600 diff lines are shown. Download the complete patch.
Documentation/core-api/printk-formats.rst
View filediff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index 160e710..9be6de4 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -79,7 +79,19 @@ Pointers printed without a specifier extension (i.e unadorned %p) are
hashed to prevent leaking information about the kernel memory layout. This
has the added benefit of providing a unique identifier. On 64-bit machines
the first 32 bits are zeroed. The kernel will print ``(ptrval)`` until it
-gathers enough entropy. If you *really* want the address see %px below.
+gathers enough entropy.
+
+When possible, use specialised modifiers such as %pS or %pB (described below)
+to avoid the need of providing an unhashed address that has to be interpreted
+post-hoc. If not possible, and the aim of printing the address is to provide
+more information for debugging, use %p and boot the kernel with the
+``no_hash_pointers`` parameter during debugging, which will print all %p
+addresses unmodified. If you *really* always want the unmodified address, see
+%px below.
+
+If (and only if) you are printing addresses as a content of a virtual file in
+e.g. procfs or sysfs (using e.g. seq_printf(), not printk()) read by a
+userspace process, use the %pK modifier described below instead of %p or %px.
Error Pointers
--------------
@@ -139,6 +151,11 @@ For printing kernel pointers which should be hidden from unprivileged
users. The behaviour of %pK depends on the kptr_restrict sysctl - see
Documentation/admin-guide/sysctl/kernel.rst for more details.
+This modifier is *only* intended when producing content of a file read by
+userspace from e.g. procfs or sysfs, not for dmesg. Please refer to the
+section about %p above for discussion about how to manage hashing pointers
+in printk().
+
Unmodified Addresses
--------------------
@@ -153,6 +170,13 @@ equivalent to %lx (or %lu). %px is preferred because it is more uniquely
grep'able. If in the future we need to modify the way the kernel handles
printing pointers we will be better equipped to find the call sites.
+Before using %px, consider if using %p is sufficient together with enabling the
+``no_hash_pointers`` kernel parameter during debugging sessions (see the %p
+description above). One valid scenario for %px might be printing information
+immediately before a panic, which prevents any sensitive information to be
+exploited anyway, and with %px there would be no need to reproduce the panic
+with no_hash_pointers.
+
Pointer Differences
-------------------
@@ -540,7 +564,7 @@ Flags bitfields such as page flags, gfp_flags
::
- %pGp referenced|uptodate|lru|active|private
+ %pGp referenced|uptodate|lru|active|private|node=0|zone=2|lastcpupid=0x1fffff
%pGg GFP_USER|GFP_DMA32|GFP_NOWARN
%pGv read|exec|mayread|maywrite|mayexec|denywrite
MAINTAINERS
View filediff --git a/MAINTAINERS b/MAINTAINERS
index 411f98d..04e7de8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14535,7 +14535,7 @@ F: kernel/sched/psi.c
PRINTK
M: Petr Mladek <[email protected]>
-M: Sergey Senozhatsky <[email protected]>
+M: Sergey Senozhatsky <[email protected]>
R: Steven Rostedt <[email protected]>
R: John Ogness <[email protected]>
S: Maintained
@@ -19388,7 +19388,7 @@ F: drivers/net/vrf.c
VSPRINTF
M: Petr Mladek <[email protected]>
M: Steven Rostedt <[email protected]>
-M: Sergey Senozhatsky <[email protected]>
+M: Sergey Senozhatsky <[email protected]>
R: Andy Shevchenko <[email protected]>
R: Rasmus Villemoes <[email protected]>
S: Maintained
@@ -20039,7 +20039,7 @@ F: drivers/staging/media/zoran/
ZRAM COMPRESSED RAM BLOCK DEVICE DRVIER
M: Minchan Kim <[email protected]>
M: Nitin Gupta <[email protected]>
-R: Sergey Senozhatsky <[email protected]>
+R: Sergey Senozhatsky <[email protected]>
S: Maintained
F: Documentation/admin-guide/blockdev/zram.rst
@@ -20053,7 +20053,7 @@ F: drivers/tty/serial/zs.*
ZSMALLOC COMPRESSED SLAB MEMORY ALLOCATOR
M: Minchan Kim <[email protected]>
M: Nitin Gupta <[email protected]>
-R: Sergey Senozhatsky <[email protected]>
+R: Sergey Senozhatsky <[email protected]>
S: Maintained
F: Documentation/vm/zsmalloc.rst
arch/powerpc/kernel/nvram_64.c
View filediff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
index 532f226..3c8d9bb 100644
--- a/arch/powerpc/kernel/nvram_64.c
+++ b/arch/powerpc/kernel/nvram_64.c
@@ -647,6 +647,7 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
{
struct oops_log_info *oops_hdr = (struct oops_log_info *)oops_buf;
static unsigned int oops_count = 0;
+ static struct kmsg_dump_iter iter;
static bool panicking = false;
static DEFINE_SPINLOCK(lock);
unsigned long flags;
@@ -681,13 +682,14 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
return;
if (big_oops_buf) {
- kmsg_dump_get_buffer(dumper, false,
+ kmsg_dump_rewind(&iter);
+ kmsg_dump_get_buffer(&iter, false,
big_oops_buf, big_oops_buf_sz, &text_len);
rc = zip_oops(text_len);
}
if (rc != 0) {
- kmsg_dump_rewind(dumper);
- kmsg_dump_get_buffer(dumper, false,
+ kmsg_dump_rewind(&iter);
+ kmsg_dump_get_buffer(&iter, false,
oops_data, oops_data_sz, &text_len);
err_type = ERR_TYPE_KERNEL_PANIC;
oops_hdr->version = cpu_to_be16(OOPS_HDR_VERSION);
arch/powerpc/xmon/xmon.c
View filediff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 3fe3749..bf7d696 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -3001,7 +3001,7 @@ print_address(unsigned long addr)
static void
dump_log_buf(void)
{
- struct kmsg_dumper dumper = { .active = 1 };
+ struct kmsg_dump_iter iter;
unsigned char buf[128];
size_t len;
@@ -3013,9 +3013,9 @@ dump_log_buf(void)
catch_memory_errors = 1;
sync();
- kmsg_dump_rewind_nolock(&dumper);
+ kmsg_dump_rewind(&iter);
xmon_start_pagination();
- while (kmsg_dump_get_line_nolock(&dumper, false, buf, sizeof(buf), &len)) {
+ while (kmsg_dump_get_line(&iter, false, buf, sizeof(buf), &len)) {
buf[len] = '\0';
printf("%s", buf);
}
arch/um/kernel/kmsg_dump.c
View filediff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
index 6516ef1..0224fcb 100644
--- a/arch/um/kernel/kmsg_dump.c
+++ b/arch/um/kernel/kmsg_dump.c
@@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/kmsg_dump.h>
+#include <linux/spinlock.h>
#include <linux/console.h>
#include <linux/string.h>
#include <shared/init.h>
@@ -9,8 +10,11 @@
static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
enum kmsg_dump_reason reason)
{
+ static struct kmsg_dump_iter iter;
+ static DEFINE_SPINLOCK(lock);
static char line[1024];
struct console *con;
+ unsigned long flags;
size_t len = 0;
/* only dump kmsg when no console is available */
@@ -29,11 +33,18 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
if (con)
return;
+ if (!spin_trylock_irqsave(&lock, flags))
+ return;
+
+ kmsg_dump_rewind(&iter);
+
printf("kmsg_dump:\n");
- while (kmsg_dump_get_line(dumper, true, line, sizeof(line), &len)) {
+ while (kmsg_dump_get_line(&iter, true, line, sizeof(line), &len)) {
line[len] = '\0';
printf("%s", line);
}
+
+ spin_unlock_irqrestore(&lock, flags);
}
static struct kmsg_dumper kmsg_dumper = {
drivers/hv/vmbus_drv.c
View filediff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index b12d682..92cb3f7 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1399,6 +1399,7 @@ static irqreturn_t vmbus_percpu_isr(int irq, void *dev_id)
static void hv_kmsg_dump(struct kmsg_dumper *dumper,
enum kmsg_dump_reason reason)
{
+ struct kmsg_dump_iter iter;
size_t bytes_written;
/* We are only interested in panics. */
@@ -1409,7 +1410,8 @@ static void hv_kmsg_dump(struct kmsg_dumper *dumper,
* Write dump contents to the page. No need to synchronize; panic should
* be single-threaded.
*/
- kmsg_dump_get_buffer(dumper, false, hv_panic_page, HV_HYP_PAGE_SIZE,
+ kmsg_dump_rewind(&iter);
+ kmsg_dump_get_buffer(&iter, false, hv_panic_page, HV_HYP_PAGE_SIZE,
&bytes_written);
if (!bytes_written)
return;
drivers/mtd/mtdoops.c
View filediff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index 774970b..862c4a8 100644
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -52,6 +52,7 @@ static struct mtdoops_context {
int nextcount;
unsigned long *oops_page_used;
+ unsigned long oops_buf_busy;
void *oops_buf;
} oops_cxt;
@@ -180,6 +181,9 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
u32 *hdr;
int ret;
+ if (test_and_set_bit(0, &cxt->oops_buf_busy))
+ return;
+
/* Add mtdoops header to the buffer */
hdr = cxt->oops_buf;
hdr[0] = cxt->nextcount;
@@ -190,7 +194,7 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
record_size, &retlen, cxt->oops_buf);
if (ret == -EOPNOTSUPP) {
printk(KERN_ERR "mtdoops: Cannot write from panic without panic_write\n");
- return;
+ goto out;
}
} else
ret = mtd_write(mtd, cxt->nextpage * record_size,
@@ -203,6 +207,8 @@ static void mtdoops_write(struct mtdoops_context *cxt, int panic)
memset(cxt->oops_buf, 0xff, record_size);
mtdoops_inc_counter(cxt);
+out:
+ clear_bit(0, &cxt->oops_buf_busy);
}
static void mtdoops_workfunc_write(struct work_struct *work)
@@ -271,13 +277,19 @@ static void mtdoops_do_dump(struct kmsg_dumper *dumper,
{
struct mtdoops_context *cxt = container_of(dumper,
struct mtdoops_context, dump);
+ struct kmsg_dump_iter iter;
/* Only dump oopses if dump_oops is set */
if (reason == KMSG_DUMP_OOPS && !dump_oops)
return;
- kmsg_dump_get_buffer(dumper, true, cxt->oops_buf + MTDOOPS_HEADER_SIZE,
+ kmsg_dump_rewind(&iter);
+
+ if (test_and_set_bit(0, &cxt->oops_buf_busy))
+ return;
+ kmsg_dump_get_buffer(&iter, true, cxt->oops_buf + MTDOOPS_HEADER_SIZE,
record_size - MTDOOPS_HEADER_SIZE, NULL);
+ clear_bit(0, &cxt->oops_buf_busy);
if (reason != KMSG_DUMP_OOPS) {
/* Panics must be written immediately */
@@ -394,6 +406,7 @@ static int __init mtdoops_init(void)
return -ENOMEM;
}
memset(cxt->oops_buf, 0xff, record_size);
+ cxt->oops_buf_busy = 0;
INIT_WORK(&cxt->work_erase, mtdoops_workfunc_erase);
INIT_WORK(&cxt->work_write, mtdoops_workfunc_write);
fs/pstore/platform.c
View filediff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index d963ae7..b9614db 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -385,6 +385,7 @@ void pstore_record_init(struct pstore_record *record,
static void pstore_dump(struct kmsg_dumper *dumper,
enum kmsg_dump_reason reason)
{
+ struct kmsg_dump_iter iter;
unsigned long total = 0;
const char *why;
unsigned int part = 1;
@@ -405,6 +406,8 @@ static void pstore_dump(struct kmsg_dumper *dumper,
}
}
+ kmsg_dump_rewind(&iter);
+
oopscount++;
while (total < kmsg_bytes) {
char *dst;
@@ -435,7 +438,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
dst_size -= header_size;
/* Write dump contents. */
- if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
+ if (!kmsg_dump_get_buffer(&iter, true, dst + header_size,
dst_size, &dump_size))
break;
include/linux/kmsg_dump.h
View filediff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
index 3378bcb..906521c 100644
--- a/include/linux/kmsg_dump.h
+++ b/include/linux/kmsg_dump.h
@@ -30,6 +30,16 @@ enum kmsg_dump_reason {
};
/**
+ * struct kmsg_dump_iter - iterator for retrieving kernel messages
+ * @cur_seq: Points to the oldest message to dump
+ * @next_seq: Points after the newest message to dump
+ */
+struct kmsg_dump_iter {
+ u64 cur_seq;
+ u64 next_seq;
+};
+
+/**
* struct kmsg_dumper - kernel crash message dumper structure
* @list: Entry in the dumper list (private)
* @dump: Call into dumping code which will retrieve the data with
@@ -41,31 +51,19 @@ struct kmsg_dumper {
struct list_head list;
void (*dump)(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason);
enum kmsg_dump_reason max_reason;
- bool active;
bool registered;
-
- /* private state of the kmsg iterator */
- u32 cur_idx;
- u32 next_idx;
- u64 cur_seq;
- u64 next_seq;
};
#ifdef CONFIG_PRINTK
void kmsg_dump(enum kmsg_dump_reason reason);
-bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog,
- char *line, size_t size, size_t *len);
-
-bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
+bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,
char *line, size_t size, size_t *len);
-bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
- char *buf, size_t size, size_t *len);
-
-void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper);
+bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog,
+ char *buf, size_t size, size_t *len_out);
-void kmsg_dump_rewind(struct kmsg_dumper *dumper);
+void kmsg_dump_rewind(struct kmsg_dump_iter *iter);
int kmsg_dump_register(struct kmsg_dumper *dumper);
@@ -77,30 +75,19 @@ static inline void kmsg_dump(enum kmsg_dump_reason reason)
{
}
-static inline bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper,
- bool syslog, const char *line,
- size_t size, size_t *len)
-{
- return false;
-}
-
-static inline bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
+static inline bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,
const char *line, size_t size, size_t *len)
{
return false;
}
-static inline bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
+static inline bool kmsg_dump_get_buffer(struct kmsg_dump_iter *iter, bool syslog,
char *buf, size_t size, size_t *len)
{
return false;
}
-static inline void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper)
-{
-}
-
-static inline void kmsg_dump_rewind(struct kmsg_dumper *dumper)
+static inline void kmsg_dump_rewind(struct kmsg_dump_iter *iter)
{
}
kernel/debug/kdb/kdb_main.c
View filediff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 405d24a..1baa96a 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -2077,7 +2077,7 @@ static int kdb_dmesg(int argc, const char **argv)
int adjust = 0;
int n = 0;
int skip = 0;
- struct kmsg_dumper dumper = { .active = 1 };
+ struct kmsg_dump_iter iter;
size_t len;
char buf[201];
@@ -2102,8 +2102,8 @@ static int kdb_dmesg(int argc, const char **argv)
kdb_set(2, setargs);
}
- kmsg_dump_rewind_nolock(&dumper);
- while (kmsg_dump_get_line_nolock(&dumper, 1, NULL, 0, NULL))
+ kmsg_dump_rewind(&iter);
+ while (kmsg_dump_get_line(&iter, 1, NULL, 0, NULL))
n++;
if (lines < 0) {
@@ -2135,8 +2135,8 @@ static int kdb_dmesg(int argc, const char **argv)
if (skip >= n || skip < 0)
return 0;
- kmsg_dump_rewind_nolock(&dumper);
- while (kmsg_dump_get_line_nolock(&dumper, 1, buf, sizeof(buf), &len)) {
+ kmsg_dump_rewind(&iter);
+ while (kmsg_dump_get_line(&iter, 1, buf, sizeof(buf), &len)) {
if (skip) {
skip--;
continue;
kernel/printk/internal.h
View filediff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index 3a8fd49..51615c9 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -12,8 +12,6 @@
#define PRINTK_NMI_CONTEXT_OFFSET 0x010000000
-extern raw_spinlock_t logbuf_lock;
-
__printf(4, 0)
int vprintk_store(int facility, int level,
const struct dev_printk_info *dev_info,
@@ -21,7 +19,6 @@ int vprintk_store(int facility, int level,
__printf(1, 0) int vprintk_default(const char *fmt, va_list args);
__printf(1, 0) int vprintk_deferred(const char *fmt, va_list args);
-__printf(1, 0) int vprintk_func(const char *fmt, va_list args);
void __printk_safe_enter(void);
void __printk_safe_exit(void);
@@ -56,10 +53,8 @@ void defer_console_output(void);
#else
-__printf(1, 0) int vprintk_func(const char *fmt, va_list args) { return 0; }
-
/*
- * In !PRINTK builds we still export logbuf_lock spin_lock, console_sem
+ * In !PRINTK builds we still export console_sem
* semaphore and some of console functions (console_unlock()/etc.), so
* printk-safe must preserve the existing local IRQ guarantees.
*/
kernel/printk/printk.c
View filediff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 575a34b..421c355 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -262,7 +262,7 @@ static void __up_console_sem(unsigned long ip)
* definitely not the perfect debug tool (we don't know if _WE_
* hold it and are racing, but it helps tracking those weird code
* paths in the console code where we end up in places I want
- * locked without the console sempahore held).
+ * locked without the console semaphore held).
*/
static int console_locked, console_suspended;
@@ -355,62 +355,50 @@ enum log_flags {
LOG_CONT = 8, /* text is a fragment of a continuation line */
};
-/*
- * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken
- * within the scheduler's rq lock. It must be released before calling
- * console_unlock() or anything else that might wake up a process.
- */
-DEFINE_RAW_SPINLOCK(logbuf_lock);
-
-/*
- * Helper macros to lock/unlock logbuf_lock and switch between
- * printk-safe/unsafe modes.
- */
-#define logbuf_lock_irq() \
- do { \
- printk_safe_enter_irq(); \
- raw_spin_lock(&logbuf_lock); \
- } while (0)
-
-#define logbuf_unlock_irq() \
- do { \
- raw_spin_unlock(&logbuf_lock); \
- printk_safe_exit_irq(); \
- } while (0)
-
-#define logbuf_lock_irqsave(flags) \
- do { \
- printk_safe_enter_irqsave(flags); \
- raw_spin_lock(&logbuf_lock); \
- } while (0)
-
-#define logbuf_unlock_irqrestore(flags) \
- do { \
- raw_spin_unlock(&logbuf_lock); \
- printk_safe_exit_irqrestore(flags); \
- } while (0)
+/* syslog_lock protects syslog_* variables and write access to clear_seq. */
+static DEFINE_RAW_SPINLOCK(syslog_lock);
#ifdef CONFIG_PRINTK
DECLARE_WAIT_QUEUE_HEAD(log_wait);
+/* All 3 protected by @syslog_lock. */
/* the next printk record to read by syslog(READ) or /proc/kmsg */
static u64 syslog_seq;
static size_t syslog_partial;
static bool syslog_time;
+/* All 3 protected by @console_sem. */
/* the next printk record to write to the console */
static u64 console_seq;
static u64 exclusive_console_stop_seq;
static unsigned long console_dropped;
-/* the next printk record to read after the last 'clear' command */
-static u64 clear_seq;
+struct latched_seq {
+ seqcount_latch_t latch;
+ u64 val[2];
+};
+
+/*
+ * The next printk record to read after the last 'clear' command. There are
+ * two copies (updated with seqcount_latch) so that reads can locklessly
+ * access a valid value. Writers are synchronized by @syslog_lock.
+ */
+static struct latched_seq clear_seq = {
+ .latch = SEQCNT_LATCH_ZERO(clear_seq.latch),
+ .val[0] = 0,
+ .val[1] = 0,
+};
#ifdef CONFIG_PRINTK_CALLER
#define PREFIX_MAX 48
#else
#define PREFIX_MAX 32
#endif
-#define LOG_LINE_MAX (1024 - PREFIX_MAX)
+
+/* the maximum size of a formatted record (i.e. with prefix added per line) */
+#define CONSOLE_LOG_MAX 1024
+
+/* the maximum size allowed to be reserved for a record */
+#define LOG_LINE_MAX (CONSOLE_LOG_MAX - PREFIX_MAX)
#define LOG_LEVEL(v) ((v) & 0x07)
#define LOG_FACILITY(v) ((v) >> 3 & 0xff)
@@ -452,6 +440,31 @@ bool printk_percpu_data_ready(void)
return __printk_percpu_data_ready;
}
+/* Must be called under syslog_lock. */
+static void latched_seq_write(struct latched_seq *ls, u64 val)
+{
+ raw_write_seqcount_latch(&ls->latch);
+ ls->val[0] = val;
+ raw_write_seqcount_latch(&ls->latch);
+ ls->val[1] = val;
+}
+
+/* Can be called from any context. */
+static u64 latched_seq_read_nolock(struct latched_seq *ls)
+{
+ unsigned int seq;
+ unsigned int idx;
+ u64 val;
+
+ do {
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kernel/printk/printk_safe.c
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lib/test_printf.c
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lib/vsprintf.c
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mm/slub.c
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