diff options
| -rw-r--r-- | include/linux/console.h | 2 | ||||
| -rw-r--r-- | kernel/printk/internal.h | 1 | ||||
| -rw-r--r-- | kernel/printk/nbcon.c | 26 | ||||
| -rw-r--r-- | kernel/printk/printk.c | 11 |
4 files changed, 40 insertions, 0 deletions
diff --git a/include/linux/console.h b/include/linux/console.h index 788ce9c829f6..eba367bf605d 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -325,6 +325,7 @@ struct nbcon_write_context { * @nbcon_state: State for nbcon consoles * @nbcon_seq: Sequence number of the next record for nbcon to print * @nbcon_device_ctxt: Context available for non-printing operations + * @nbcon_prev_seq: Seq num the previous nbcon owner was assigned to print * @pbufs: Pointer to nbcon private buffer * @kthread: Printer kthread for this console * @rcuwait: RCU-safe wait object for @kthread waking @@ -459,6 +460,7 @@ struct console { atomic_t __private nbcon_state; atomic_long_t __private nbcon_seq; struct nbcon_context __private nbcon_device_ctxt; + atomic_long_t __private nbcon_prev_seq; struct printk_buffers *pbufs; struct task_struct *kthread; diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h index 8166e24f8780..c365d25b13c7 100644 --- a/kernel/printk/internal.h +++ b/kernel/printk/internal.h @@ -319,4 +319,5 @@ bool printk_get_next_message(struct printk_message *pmsg, u64 seq, #ifdef CONFIG_PRINTK void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped); +void console_prepend_replay(struct printk_message *pmsg); #endif diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c index 5146ce9853a3..98440889d222 100644 --- a/kernel/printk/nbcon.c +++ b/kernel/printk/nbcon.c @@ -946,7 +946,9 @@ static bool nbcon_emit_next_record(struct nbcon_write_context *wctxt, bool use_a .pbufs = ctxt->pbufs, }; unsigned long con_dropped; + struct nbcon_state cur; unsigned long dropped; + unsigned long ulseq; /* * This function should never be called for consoles that have not @@ -987,6 +989,29 @@ static bool nbcon_emit_next_record(struct nbcon_write_context *wctxt, bool use_a if (dropped && !is_extended) console_prepend_dropped(&pmsg, dropped); + /* + * If the previous owner was assigned the same record, this context + * has taken over ownership and is replaying the record. Prepend a + * message to let the user know the record is replayed. + */ + ulseq = atomic_long_read(&ACCESS_PRIVATE(con, nbcon_prev_seq)); + if (__ulseq_to_u64seq(prb, ulseq) == pmsg.seq) { + console_prepend_replay(&pmsg); + } else { + /* + * Ensure this context is still the owner before trying to + * update @nbcon_prev_seq. Otherwise the value in @ulseq may + * not be from the previous owner and instead be some later + * value from the context that took over ownership. + */ + nbcon_state_read(con, &cur); + if (!nbcon_context_can_proceed(ctxt, &cur)) + return false; + + atomic_long_try_cmpxchg(&ACCESS_PRIVATE(con, nbcon_prev_seq), &ulseq, + __u64seq_to_ulseq(pmsg.seq)); + } + if (!nbcon_context_exit_unsafe(ctxt)) return false; @@ -1646,6 +1671,7 @@ bool nbcon_alloc(struct console *con) rcuwait_init(&con->rcuwait); init_irq_work(&con->irq_work, nbcon_irq_work); + atomic_long_set(&ACCESS_PRIVATE(con, nbcon_prev_seq), -1UL); nbcon_state_set(con, &state); /* diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index e9458569bcfd..c27dc54f4151 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2903,6 +2903,17 @@ void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped) } /* + * Prepend the message in @pmsg->pbufs->outbuf with a "replay message". + * @pmsg->outbuf_len is updated appropriately. + * + * @pmsg is the printk message to prepend. + */ +void console_prepend_replay(struct printk_message *pmsg) +{ + console_prepend_message(pmsg, "** replaying previous printk message **\n"); +} + +/* * Read and format the specified record (or a later record if the specified * record is not available). * |