diff options
Diffstat (limited to 'debian/patches-rt/0093-printk-Wait-for-all-reserved-records-with-pr_flush.patch')
| -rw-r--r-- | debian/patches-rt/0093-printk-Wait-for-all-reserved-records-with-pr_flush.patch | 170 |
1 files changed, 0 insertions, 170 deletions
diff --git a/debian/patches-rt/0093-printk-Wait-for-all-reserved-records-with-pr_flush.patch b/debian/patches-rt/0093-printk-Wait-for-all-reserved-records-with-pr_flush.patch deleted file mode 100644 index 661aea210..000000000 --- a/debian/patches-rt/0093-printk-Wait-for-all-reserved-records-with-pr_flush.patch +++ /dev/null @@ -1,170 +0,0 @@ -From: John Ogness <john.ogness@linutronix.de> -Date: Mon, 6 Nov 2023 14:59:55 +0000 -Subject: [PATCH 093/134] printk: Wait for all reserved records with pr_flush() -Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz - -Currently pr_flush() will only wait for records that were -available to readers at the time of the call (using -prb_next_seq()). But there may be more records (non-finalized) -that have following finalized records. pr_flush() should wait -for these to print as well. Particularly because any trailing -finalized records may be the messages that the calling context -wants to ensure are printed. - -Add a new ringbuffer function prb_next_reserve_seq() to return -the sequence number following the most recently reserved record. -This guarantees that pr_flush() will wait until all current -printk() messages (completed or in progress) have been printed. - -Fixes: 3b604ca81202 ("printk: add pr_flush()") -Signed-off-by: John Ogness <john.ogness@linutronix.de> -Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> ---- - kernel/printk/printk.c | 2 - kernel/printk/printk_ringbuffer.c | 113 ++++++++++++++++++++++++++++++++++++++ - kernel/printk/printk_ringbuffer.h | 1 - 3 files changed, 115 insertions(+), 1 deletion(-) - ---- a/kernel/printk/printk.c -+++ b/kernel/printk/printk.c -@@ -3756,7 +3756,7 @@ static bool __pr_flush(struct console *c - - might_sleep(); - -- seq = prb_next_seq(prb); -+ seq = prb_next_reserve_seq(prb); - - /* Flush the consoles so that records up to @seq are printed. */ - console_lock(); ---- a/kernel/printk/printk_ringbuffer.c -+++ b/kernel/printk/printk_ringbuffer.c -@@ -1986,6 +1986,119 @@ u64 prb_first_seq(struct printk_ringbuff - return seq; - } - -+/** -+ * prb_next_reserve_seq() - Get the sequence number after the most recently -+ * reserved record. -+ * -+ * @rb: The ringbuffer to get the sequence number from. -+ * -+ * This is the public function available to readers to see what sequence -+ * number will be assigned to the next reserved record. -+ * -+ * Note that depending on the situation, this value can be equal to or -+ * higher than the sequence number returned by prb_next_seq(). -+ * -+ * Context: Any context. -+ * Return: The sequence number that will be assigned to the next record -+ * reserved. -+ */ -+u64 prb_next_reserve_seq(struct printk_ringbuffer *rb) -+{ -+ struct prb_desc_ring *desc_ring = &rb->desc_ring; -+ unsigned long last_finalized_id; -+ atomic_long_t *state_var; -+ u64 last_finalized_seq; -+ unsigned long head_id; -+ struct prb_desc desc; -+ unsigned long diff; -+ struct prb_desc *d; -+ int err; -+ -+ /* -+ * It may not be possible to read a sequence number for @head_id. -+ * So the ID of @last_finailzed_seq is used to calculate what the -+ * sequence number of @head_id will be. -+ */ -+ -+try_again: -+ last_finalized_seq = desc_last_finalized_seq(rb); -+ -+ /* -+ * @head_id is loaded after @last_finalized_seq to ensure that it is -+ * at or beyond @last_finalized_seq. -+ * -+ * Memory barrier involvement: -+ * -+ * If desc_last_finalized_seq:A reads from -+ * desc_update_last_finalized:A, then -+ * prb_next_reserve_seq:A reads from desc_reserve:D. -+ * -+ * Relies on: -+ * -+ * RELEASE from desc_reserve:D to desc_update_last_finalized:A -+ * matching -+ * ACQUIRE from desc_last_finalized_seq:A to prb_next_reserve_seq:A -+ * -+ * Note: desc_reserve:D and desc_update_last_finalized:A can be -+ * different CPUs. However, the desc_update_last_finalized:A CPU -+ * (which performs the release) must have previously seen -+ * desc_read:C, which implies desc_reserve:D can be seen. -+ */ -+ head_id = atomic_long_read(&desc_ring->head_id); /* LMM(prb_next_reserve_seq:A) */ -+ -+ d = to_desc(desc_ring, last_finalized_seq); -+ state_var = &d->state_var; -+ -+ /* Extract the ID, used to specify the descriptor to read. */ -+ last_finalized_id = DESC_ID(atomic_long_read(state_var)); -+ -+ /* Ensure @last_finalized_id is correct. */ -+ err = desc_read_finalized_seq(desc_ring, last_finalized_id, last_finalized_seq, &desc); -+ -+ if (err == -EINVAL) { -+ if (last_finalized_seq == 0) { -+ /* -+ * @last_finalized_seq still contains its initial -+ * value. Probably no record has been finalized yet. -+ * This means the ringbuffer is not yet full and the -+ * @head_id value can be used directly (subtracting -+ * off the id value corresponding to seq=0). -+ */ -+ -+ /* -+ * Because of hack#2 of the bootstrapping phase, the -+ * @head_id initial value must be handled separately. -+ */ -+ if (head_id == DESC0_ID(desc_ring->count_bits)) -+ return 0; -+ -+ /* -+ * The @head_id is initialized such that the first -+ * increment will yield the first record (seq=0). -+ * Therefore use the initial value +1 as the base to -+ * subtract from @head_id. -+ */ -+ last_finalized_id = DESC0_ID(desc_ring->count_bits) + 1; -+ } else { -+ /* Record must have been overwritten. Try again. */ -+ goto try_again; -+ } -+ } -+ -+ /* -+ * @diff is the number of records beyond the last record available -+ * to readers. -+ */ -+ diff = head_id - last_finalized_id; -+ -+ /* -+ * @head_id points to the most recently reserved record, but this -+ * function returns the sequence number that will be assigned to the -+ * next (not yet reserved) record. Thus +1 is needed. -+ */ -+ return (last_finalized_seq + diff + 1); -+} -+ - /* - * Non-blocking read of a record. - * ---- a/kernel/printk/printk_ringbuffer.h -+++ b/kernel/printk/printk_ringbuffer.h -@@ -395,6 +395,7 @@ bool prb_read_valid_info(struct printk_r - u64 prb_first_seq(struct printk_ringbuffer *rb); - u64 prb_first_valid_seq(struct printk_ringbuffer *rb); - u64 prb_next_seq(struct printk_ringbuffer *rb); -+u64 prb_next_reserve_seq(struct printk_ringbuffer *rb); - - #ifdef CONFIG_64BIT - |