diff options
Diffstat (limited to 'features/rt/printk-remove-deferred-printing.patch')
| -rw-r--r-- | features/rt/printk-remove-deferred-printing.patch | 432 |
1 files changed, 432 insertions, 0 deletions
diff --git a/features/rt/printk-remove-deferred-printing.patch b/features/rt/printk-remove-deferred-printing.patch new file mode 100644 index 00000000..2777df6c --- /dev/null +++ b/features/rt/printk-remove-deferred-printing.patch @@ -0,0 +1,432 @@ +From 67ba4172040ce8b57495aabc320404e9e7379e7a Mon Sep 17 00:00:00 2001 +From: John Ogness <john.ogness@linutronix.de> +Date: Mon, 30 Nov 2020 01:42:08 +0106 +Subject: [PATCH 031/191] printk: remove deferred printing + +Since printing occurs either atomically or from the printing +kthread, there is no need for any deferring or tracking possible +recursion paths. Remove all printk context tracking. + +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + arch/arm/kernel/smp.c | 2 - + arch/powerpc/kexec/crash.c | 3 -- + include/linux/hardirq.h | 2 - + include/linux/printk.h | 12 ----- + kernel/printk/Makefile | 1 - + kernel/printk/internal.h | 70 ----------------------------- + kernel/printk/printk.c | 58 +++++++++--------------- + kernel/printk/printk_safe.c | 89 ------------------------------------- + kernel/trace/trace.c | 2 - + 9 files changed, 22 insertions(+), 217 deletions(-) + delete mode 100644 kernel/printk/internal.h + delete mode 100644 kernel/printk/printk_safe.c + +diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c +index 74679240a9d8..0dd2d733ad62 100644 +--- a/arch/arm/kernel/smp.c ++++ b/arch/arm/kernel/smp.c +@@ -668,9 +668,7 @@ static void do_handle_IPI(int ipinr) + break; + + case IPI_CPU_BACKTRACE: +- printk_nmi_enter(); + nmi_cpu_backtrace(get_irq_regs()); +- printk_nmi_exit(); + break; + + default: +diff --git a/arch/powerpc/kexec/crash.c b/arch/powerpc/kexec/crash.c +index c9a889880214..d488311efab1 100644 +--- a/arch/powerpc/kexec/crash.c ++++ b/arch/powerpc/kexec/crash.c +@@ -311,9 +311,6 @@ void default_machine_crash_shutdown(struct pt_regs *regs) + unsigned int i; + int (*old_handler)(struct pt_regs *regs); + +- /* Avoid hardlocking with irresponsive CPU holding logbuf_lock */ +- printk_nmi_enter(); +- + /* + * This function is only called after the system + * has panicked or is otherwise in a critical state. +diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h +index 7c9d6a2d7e90..0926e9ca4d85 100644 +--- a/include/linux/hardirq.h ++++ b/include/linux/hardirq.h +@@ -115,7 +115,6 @@ extern void rcu_nmi_exit(void); + do { \ + lockdep_off(); \ + arch_nmi_enter(); \ +- printk_nmi_enter(); \ + BUG_ON(in_nmi() == NMI_MASK); \ + __preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET); \ + } while (0) +@@ -134,7 +133,6 @@ extern void rcu_nmi_exit(void); + do { \ + BUG_ON(!in_nmi()); \ + __preempt_count_sub(NMI_OFFSET + HARDIRQ_OFFSET); \ +- printk_nmi_exit(); \ + arch_nmi_exit(); \ + lockdep_on(); \ + } while (0) +diff --git a/include/linux/printk.h b/include/linux/printk.h +index 1ebd93581acc..153212445b68 100644 +--- a/include/linux/printk.h ++++ b/include/linux/printk.h +@@ -155,18 +155,6 @@ static inline __printf(1, 2) __cold + void early_printk(const char *s, ...) { } + #endif + +-#ifdef CONFIG_PRINTK_NMI +-extern void printk_nmi_enter(void); +-extern void printk_nmi_exit(void); +-extern void printk_nmi_direct_enter(void); +-extern void printk_nmi_direct_exit(void); +-#else +-static inline void printk_nmi_enter(void) { } +-static inline void printk_nmi_exit(void) { } +-static inline void printk_nmi_direct_enter(void) { } +-static inline void printk_nmi_direct_exit(void) { } +-#endif /* PRINTK_NMI */ +- + struct dev_printk_info; + + #ifdef CONFIG_PRINTK +diff --git a/kernel/printk/Makefile b/kernel/printk/Makefile +index eee3dc9b60a9..59cb24e25f00 100644 +--- a/kernel/printk/Makefile ++++ b/kernel/printk/Makefile +@@ -1,5 +1,4 @@ + # SPDX-License-Identifier: GPL-2.0-only + obj-y = printk.o +-obj-$(CONFIG_PRINTK) += printk_safe.o + obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille.o + obj-$(CONFIG_PRINTK) += printk_ringbuffer.o +diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h +deleted file mode 100644 +index e108b2ece8c7..000000000000 +--- a/kernel/printk/internal.h ++++ /dev/null +@@ -1,70 +0,0 @@ +-/* SPDX-License-Identifier: GPL-2.0-or-later */ +-/* +- * internal.h - printk internal definitions +- */ +-#include <linux/percpu.h> +- +-#ifdef CONFIG_PRINTK +- +-#define PRINTK_SAFE_CONTEXT_MASK 0x007ffffff +-#define PRINTK_NMI_DIRECT_CONTEXT_MASK 0x008000000 +-#define PRINTK_NMI_CONTEXT_MASK 0xff0000000 +- +-#define PRINTK_NMI_CONTEXT_OFFSET 0x010000000 +- +-__printf(4, 0) +-int vprintk_store(int facility, int level, +- const struct dev_printk_info *dev_info, +- const char *fmt, va_list args); +- +-__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); +- +-bool printk_percpu_data_ready(void); +- +-#define printk_safe_enter_irqsave(flags) \ +- do { \ +- local_irq_save(flags); \ +- __printk_safe_enter(); \ +- } while (0) +- +-#define printk_safe_exit_irqrestore(flags) \ +- do { \ +- __printk_safe_exit(); \ +- local_irq_restore(flags); \ +- } while (0) +- +-#define printk_safe_enter_irq() \ +- do { \ +- local_irq_disable(); \ +- __printk_safe_enter(); \ +- } while (0) +- +-#define printk_safe_exit_irq() \ +- do { \ +- __printk_safe_exit(); \ +- local_irq_enable(); \ +- } while (0) +- +-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 console_sem +- * semaphore and some of console functions (console_unlock()/etc.), so +- * printk-safe must preserve the existing local IRQ guarantees. +- */ +-#define printk_safe_enter_irqsave(flags) local_irq_save(flags) +-#define printk_safe_exit_irqrestore(flags) local_irq_restore(flags) +- +-#define printk_safe_enter_irq() local_irq_disable() +-#define printk_safe_exit_irq() local_irq_enable() +- +-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 e2dd2abfb855..d1b25ac5c73b 100644 +--- a/kernel/printk/printk.c ++++ b/kernel/printk/printk.c +@@ -45,6 +45,7 @@ + #include <linux/ctype.h> + #include <linux/uio.h> + #include <linux/kthread.h> ++#include <linux/kdb.h> + #include <linux/clocksource.h> + #include <linux/sched/clock.h> + #include <linux/sched/debug.h> +@@ -60,7 +61,6 @@ + #include "printk_ringbuffer.h" + #include "console_cmdline.h" + #include "braille.h" +-#include "internal.h" + + int console_printk[4] = { + CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */ +@@ -227,19 +227,7 @@ static int nr_ext_console_drivers; + + static int __down_trylock_console_sem(unsigned long ip) + { +- int lock_failed; +- unsigned long flags; +- +- /* +- * Here and in __up_console_sem() we need to be in safe mode, +- * because spindump/WARN/etc from under console ->lock will +- * deadlock in printk()->down_trylock_console_sem() otherwise. +- */ +- printk_safe_enter_irqsave(flags); +- lock_failed = down_trylock(&console_sem); +- printk_safe_exit_irqrestore(flags); +- +- if (lock_failed) ++ if (down_trylock(&console_sem)) + return 1; + mutex_acquire(&console_lock_dep_map, 0, 1, ip); + return 0; +@@ -248,13 +236,9 @@ static int __down_trylock_console_sem(unsigned long ip) + + static void __up_console_sem(unsigned long ip) + { +- unsigned long flags; +- + mutex_release(&console_lock_dep_map, ip); + +- printk_safe_enter_irqsave(flags); + up(&console_sem); +- printk_safe_exit_irqrestore(flags); + } + #define up_console_sem() __up_console_sem(_RET_IP_) + +@@ -426,7 +410,7 @@ static struct printk_ringbuffer *prb = &printk_rb_static; + */ + static bool __printk_percpu_data_ready __read_mostly; + +-bool printk_percpu_data_ready(void) ++static bool printk_percpu_data_ready(void) + { + return __printk_percpu_data_ready; + } +@@ -1060,7 +1044,6 @@ void __init setup_log_buf(int early) + struct printk_record r; + size_t new_descs_size; + size_t new_infos_size; +- unsigned long flags; + char *new_log_buf; + unsigned int free; + u64 seq; +@@ -1958,9 +1941,9 @@ static u16 printk_sprint(char *text, u16 size, int facility, enum log_flags *lfl + } + + __printf(4, 0) +-int vprintk_store(int facility, int level, +- const struct dev_printk_info *dev_info, +- const char *fmt, va_list args) ++static int vprintk_store(int facility, int level, ++ const struct dev_printk_info *dev_info, ++ const char *fmt, va_list args) + { + const u32 caller_id = printk_caller_id(); + struct prb_reserved_entry e; +@@ -2106,11 +2089,22 @@ asmlinkage int vprintk_emit(int facility, int level, + } + EXPORT_SYMBOL(vprintk_emit); + +-int vprintk_default(const char *fmt, va_list args) ++__printf(1, 0) ++static int vprintk_default(const char *fmt, va_list args) + { + return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, fmt, args); + } +-EXPORT_SYMBOL_GPL(vprintk_default); ++ ++__printf(1, 0) ++static int vprintk_func(const char *fmt, va_list args) ++{ ++#ifdef CONFIG_KGDB_KDB ++ /* Allow to pass printk() to kdb but avoid a recursion. */ ++ if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) ++ return vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args); ++#endif ++ return vprintk_default(fmt, args); ++} + + asmlinkage int vprintk(const char *fmt, va_list args) + { +@@ -3073,18 +3067,10 @@ void wake_up_klogd(void) + preempt_enable(); + } + +-void defer_console_output(void) +-{ +-} +- +-int vprintk_deferred(const char *fmt, va_list args) ++__printf(1, 0) ++static int vprintk_deferred(const char *fmt, va_list args) + { +- int r; +- +- r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, fmt, args); +- defer_console_output(); +- +- return r; ++ return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, fmt, args); + } + + int printk_deferred(const char *fmt, ...) +diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c +deleted file mode 100644 +index 3ee2d62e80ef..000000000000 +--- a/kernel/printk/printk_safe.c ++++ /dev/null +@@ -1,89 +0,0 @@ +-// SPDX-License-Identifier: GPL-2.0-or-later +-/* +- * printk_safe.c - Safe printk for printk-deadlock-prone contexts +- */ +- +-#include <linux/preempt.h> +-#include <linux/spinlock.h> +-#include <linux/debug_locks.h> +-#include <linux/kdb.h> +-#include <linux/smp.h> +-#include <linux/cpumask.h> +-#include <linux/irq_work.h> +-#include <linux/printk.h> +-#include <linux/kprobes.h> +- +-#include "internal.h" +- +-static DEFINE_PER_CPU(int, printk_context); +- +-#ifdef CONFIG_PRINTK_NMI +- +-void noinstr printk_nmi_enter(void) +-{ +- this_cpu_add(printk_context, PRINTK_NMI_CONTEXT_OFFSET); +-} +- +-void noinstr printk_nmi_exit(void) +-{ +- this_cpu_sub(printk_context, PRINTK_NMI_CONTEXT_OFFSET); +-} +- +-/* +- * Marks a code that might produce many messages in NMI context +- * and the risk of losing them is more critical than eventual +- * reordering. +- */ +-void printk_nmi_direct_enter(void) +-{ +- if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK) +- this_cpu_or(printk_context, PRINTK_NMI_DIRECT_CONTEXT_MASK); +-} +- +-void printk_nmi_direct_exit(void) +-{ +- this_cpu_and(printk_context, ~PRINTK_NMI_DIRECT_CONTEXT_MASK); +-} +- +-#endif /* CONFIG_PRINTK_NMI */ +- +-/* Can be preempted by NMI. */ +-void __printk_safe_enter(void) +-{ +- this_cpu_inc(printk_context); +-} +- +-/* Can be preempted by NMI. */ +-void __printk_safe_exit(void) +-{ +- this_cpu_dec(printk_context); +-} +- +-__printf(1, 0) int vprintk_func(const char *fmt, va_list args) +-{ +-#ifdef CONFIG_KGDB_KDB +- /* Allow to pass printk() to kdb but avoid a recursion. */ +- if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) +- return vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args); +-#endif +- +- /* +- * Use the main logbuf even in NMI. But avoid calling console +- * drivers that might have their own locks. +- */ +- if (this_cpu_read(printk_context) & +- (PRINTK_NMI_DIRECT_CONTEXT_MASK | +- PRINTK_NMI_CONTEXT_MASK | +- PRINTK_SAFE_CONTEXT_MASK)) { +- int len; +- +- printk_safe_enter_irqsave(flags); +- len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, fmt, args); +- printk_safe_exit_irqrestore(flags); +- defer_console_output(); +- return len; +- } +- +- /* No obstacles. */ +- return vprintk_default(fmt, args); +-} +diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c +index eccb4e1187cc..a6baa9b174e4 100644 +--- a/kernel/trace/trace.c ++++ b/kernel/trace/trace.c +@@ -9404,7 +9404,6 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) + tracing_off(); + + local_irq_save(flags); +- printk_nmi_direct_enter(); + + /* Simulate the iterator */ + trace_init_global_iter(&iter); +@@ -9486,7 +9485,6 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) + atomic_dec(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); + } + atomic_dec(&dump_running); +- printk_nmi_direct_exit(); + local_irq_restore(flags); + } + EXPORT_SYMBOL_GPL(ftrace_dump); +-- +2.19.1 + |