* [RFC][PATCH 5/5] relayfs scheme-dependent code
@ 2003-07-15 15:18 Tom Zanussi
0 siblings, 0 replies; only message in thread
From: Tom Zanussi @ 2003-07-15 15:18 UTC (permalink / raw)
To: linux-kernel; +Cc: karim, bob
diff -urpN -X dontdiff linux-2.6.0-test1/fs/relayfs/relay_locking.c linux-2.6.0-test1-relayfs-printk/fs/relayfs/relay_locking.c
--- linux-2.6.0-test1/fs/relayfs/relay_locking.c Wed Dec 31 18:00:00 1969
+++ linux-2.6.0-test1-relayfs-printk/fs/relayfs/relay_locking.c Sun Jul 13 22:32:49 2003
@@ -0,0 +1,632 @@
+/*
+ * RelayFS locking scheme implementation.
+ *
+ * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com)
+ * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
+ *
+ * This file is released under the GPL.
+ */
+
+#include <asm/relay.h>
+#include "relay_locking.h"
+
+/**
+ * expand_check - check whether the channel needs expanding
+ * @rchan: the channel
+ * @active_bufs: the number of unread sub-buffers
+ *
+ * If the channel is above 1/3 full, it will be doubled in
+ * size. This low threshold has to do with the fact that we
+ * only have two buffers and they're checked during buffer
+ * switches only.
+ *
+ * Returns the suggested sub-buffer size for the new buffer.
+ *
+ * NOTE: this check will only work correctly during buffer switches.
+ */
+static u32
+expand_check(struct rchan *rchan)
+{
+ u32 bytes_ready;
+ u32 bytes_consumed;
+ u32 bytes_produced;
+ u32 new_bufsize = 0;
+ u32 cur_idx = cur_write_pos(rchan) - rchan->buf;
+
+ bytes_consumed = rchan->bufs_consumed * rchan->buf_size;
+ bytes_consumed += rchan->bytes_consumed;
+ bytes_produced = rchan->bufs_produced * rchan->buf_size;
+ bytes_produced += bytes_produced(rchan) + cur_idx;
+ if (cur_idx > rchan->buf_size)
+ bytes_produced -= rchan->buf_size;
+
+ bytes_ready = bytes_produced - bytes_consumed;
+
+ if (rchan->resize_max && !rchan->mapped && bytes_ready >
+ (rchan->n_bufs * rchan->buf_size) * RESIZE_THRESHOLD_LOCKING)
+ new_bufsize = rchan->buf_size * 2;
+
+ return new_bufsize;
+}
+
+/**
+ * shrink_check - check whether the channel needs shrinking
+ * @rchan: the channel
+ * @active_bufs: the number of unread sub-buffers
+ *
+ * If a minute has passed since the last resize, and it's no
+ * longer full, it will be shrunk to whatever size will comfortably
+ * fit the contents.
+ *
+ * Returns the suggested sub-buffer size for the new buffer.
+ */
+static u32
+shrink_check(struct rchan *rchan)
+{
+ u32 needed_bufsize;
+ struct timeval ts;
+ u32 low_water_delta;
+ u32 bytes_ready;
+ u32 bytes_consumed;
+ u32 bytes_produced;
+ u32 new_bufsize = 0;
+ u32 cur_idx = cur_write_pos(rchan) - rchan->buf;
+ u32 n;
+
+ bytes_consumed = rchan->bufs_consumed * rchan->buf_size;
+ bytes_consumed += rchan->bytes_consumed;
+ bytes_produced = rchan->bufs_produced * rchan->buf_size;
+ bytes_produced += bytes_produced(rchan);
+ if (cur_idx > rchan->buf_size)
+ bytes_produced += cur_idx - rchan->buf_size;
+ else
+ bytes_produced += cur_idx;
+
+ bytes_ready = bytes_produced - bytes_consumed;
+
+ if (!rchan->resize_min || rchan->mapped ||
+ rchan->resize_min >= rchan->n_bufs * rchan->buf_size)
+ goto out;
+
+ if (bytes_ready > (rchan->n_bufs * rchan->buf_size) * RESIZE_THRESHOLD_LOCKING) {
+ do_gettimeofday(&rchan->low_water_time);
+ goto out;
+ }
+
+ do_gettimeofday(&ts);
+ low_water_delta = calc_time_delta(&ts, &rchan->low_water_time);
+ if (low_water_delta > LOW_WATER_TIME) {
+ needed_bufsize = bytes_ready;
+
+ for (n = RELAY_MIN_BUFSIZE; n < rchan->buf_size; n *= 2) {
+ if ((n * rchan->n_bufs >= rchan->resize_min) &&
+ (n * rchan->n_bufs <= rchan->resize_max) &&
+ (n * rchan->n_bufs * RESIZE_THRESHOLD_LOCKING > needed_bufsize))
+ break;
+ }
+
+ if (n >= rchan->buf_size)
+ goto out;
+
+ new_bufsize = n;
+ }
+out:
+ return new_bufsize;
+}
+
+/**
+ * switch_buffers - switches between read and write buffers.
+ * @cur_time: current time.
+ * @cur_tsc: the TSC associated with current_time, if applicable
+ * @rchan: the channel
+ * @finalizing: if true, don't start a new buffer
+ *
+ * This should be called from with interrupts disabled.
+ */
+static void
+switch_buffers(struct timeval cur_time,
+ u32 cur_tsc,
+ struct rchan *rchan,
+ int finalizing)
+{
+ char *temp_buf;
+ char *temp_buf_end;
+ int bytes_written;
+ u32 new_bufsize;
+
+ bytes_written = rchan->callbacks->buffer_end(rchan->id,
+ cur_write_pos(rchan), write_buf_end(rchan),
+ cur_time, cur_tsc, using_tsc(rchan));
+ if (bytes_written == 0)
+ rchan->unused_bytes[rchan->buf_id % rchan->n_bufs] =
+ write_buf_end(rchan) - cur_write_pos(rchan);
+
+ new_bufsize = expand_check(rchan);
+ if (new_bufsize)
+ rchan->callbacks->needs_resize(rchan->id,
+ RELAY_RESIZE_EXPAND,
+ new_bufsize,
+ rchan->n_bufs);
+
+
+ cur_write_pos(rchan) += bytes_written;
+ temp_buf = read_buf(rchan);
+ read_buf(rchan) = write_buf(rchan);
+ write_buf(rchan) = temp_buf;
+ temp_buf_end = read_buf_end(rchan);
+ read_buf_end(rchan) = write_buf_end(rchan);
+ write_buf_end(rchan) = temp_buf_end;
+ read_limit(rchan) = read_buf_end(rchan);
+ write_limit(rchan) = write_buf_end(rchan) - rchan->end_reserve;
+ cur_write_pos(rchan) = write_buf(rchan);
+
+ rchan->buf_start_time = cur_time;
+ rchan->buf_start_tsc = cur_tsc;
+
+ rchan->buf_id++;
+ if (!packet_delivery(rchan))
+ rchan->unused_bytes[rchan->buf_id % rchan->n_bufs] = 0;
+ rchan->bufs_produced++;
+
+ if (!finalizing) {
+ bytes_written = rchan->callbacks->buffer_start(rchan->id, cur_write_pos(rchan), rchan->buf_id, cur_time, cur_tsc, using_tsc(rchan));
+ cur_write_pos(rchan) += bytes_written;
+ }
+}
+
+/**
+ * locking_reserve - reserve a slot in the trace buffer for an event.
+ * @rchan: the channel
+ * @slot_len: the length of the slot to reserve
+ * @ts: variable that will receive the time the slot was reserved
+ * @tsc: the timestamp counter associated with time
+ * @err: receives the result flags
+ * @interrupting: if this write is interrupting another, set to non-zero
+ *
+ * Returns pointer to the beginning of the reserved slot, NULL if error.
+ *
+ * The err value contains the result flags and is an ORed combination
+ * of the following:
+ *
+ * RELAY_BUFFER_SWITCH_NONE - no buffer switch occurred
+ * RELAY_EVENT_DISCARD_NONE - event should not be discarded
+ * RELAY_BUFFER_SWITCH - buffer switch occurred
+ * RELAY_EVENT_DISCARD - event should be discarded (all buffers are full)
+ * RELAY_EVENT_TOO_LONG - event won't fit into even an empty buffer
+ */
+inline char *
+locking_reserve(struct rchan *rchan,
+ u32 slot_len,
+ struct timeval *ts,
+ u32 *tsc,
+ int *err,
+ int *interrupting)
+{
+ int bytes_written;
+
+ *err = RELAY_BUFFER_SWITCH_NONE;
+
+ if (slot_len >= rchan->buf_size) {
+ *err = RELAY_WRITE_DISCARD | RELAY_WRITE_TOO_LONG;
+ rchan->events_lost++;
+ return NULL;
+ }
+
+ if (rchan->initialized == 0) {
+ rchan->initialized = 1;
+ get_timestamp(&rchan->buf_start_time,
+ &rchan->buf_start_tsc, rchan);
+ rchan->unused_bytes[0] = 0;
+ bytes_written = rchan->callbacks->buffer_start(
+ rchan->id, cur_write_pos(rchan),
+ rchan->buf_id, rchan->buf_start_time,
+ rchan->buf_start_tsc, using_tsc(rchan));
+ cur_write_pos(rchan) += bytes_written;
+ *tsc = get_time_delta(ts, rchan);
+ return cur_write_pos(rchan);
+ }
+
+ *tsc = get_time_delta(ts, rchan);
+
+ if (in_progress_event_size(rchan)) {
+ interrupted_pos(rchan) = cur_write_pos(rchan);
+ cur_write_pos(rchan) = in_progress_event_pos(rchan)
+ + in_progress_event_size(rchan)
+ + interrupting_size(rchan);
+ *interrupting = 1;
+ } else {
+ in_progress_event_pos(rchan) = cur_write_pos(rchan);
+ in_progress_event_size(rchan) = slot_len;
+ interrupting_size(rchan) = 0;
+ }
+
+ if (cur_write_pos(rchan) + slot_len > write_limit(rchan)) {
+ if (atomic_read(&rchan->suspended) == 1) {
+ *err = RELAY_WRITE_DISCARD;
+ rchan->events_lost++;
+ return NULL;
+ }
+
+ if (rchan->bufs_produced - rchan->bufs_consumed > 0) {
+ if (rchan->callbacks->buffers_full(rchan->id)) {
+ atomic_set(&rchan->suspended, 1);
+ *err = RELAY_WRITE_DISCARD;
+ rchan->events_lost++;
+ return NULL;
+ }
+ }
+
+ get_timestamp(ts, tsc, rchan);
+ switch_buffers(*ts, *tsc, rchan, 0);
+ recalc_time_delta(ts, tsc, rchan);
+ *err = RELAY_BUFFER_SWITCH;
+ }
+
+ return cur_write_pos(rchan);
+}
+
+/**
+ * locking_resume - resume a suspended channel
+ * @rchan: the channel
+ */
+inline void
+locking_resume(struct rchan *rchan)
+{
+ atomic_set(&rchan->suspended, 0);
+}
+
+
+/**
+ * lockless_commit - commit a reserved slot in the buffer
+ * @rchan: the channel
+ * @from: commit the length starting here
+ * @len: length committed
+ * @deliver: length committed
+ * @interrupting: not used
+ *
+ * Commits len bytes and calls deliver callback if applicable.
+ */
+inline void
+locking_commit(struct rchan *rchan,
+ char *from,
+ u32 len,
+ int deliver,
+ int interrupting)
+{
+ u32 new_bufsize;
+
+ cur_write_pos(rchan) += len;
+
+ if (interrupting) {
+ cur_write_pos(rchan) = interrupted_pos(rchan);
+ interrupting_size(rchan) += len;
+ } else {
+ in_progress_event_size(rchan) = 0;
+ if (interrupting_size(rchan)) {
+ cur_write_pos(rchan) += interrupting_size(rchan);
+ interrupting_size(rchan) = 0;
+ }
+ }
+
+ if (deliver) {
+ rchan->callbacks->deliver(rchan->id, from, len);
+ new_bufsize = shrink_check(rchan);
+ if (new_bufsize)
+ rchan->callbacks->needs_resize(rchan->id,
+ RELAY_RESIZE_SHRINK,
+ new_bufsize,
+ rchan->n_bufs);
+ }
+}
+
+/**
+ * locking_finalize: - finalize last buffer at end of channel use
+ * @rchan: the channel
+ */
+inline void
+locking_finalize(struct rchan *rchan)
+{
+ unsigned long int flags;
+ struct timeval time;
+ u32 tsc;
+
+ local_irq_save(flags);
+ get_timestamp(&time, &tsc, rchan);
+ switch_buffers(time, tsc, rchan, 1);
+ local_irq_restore(flags);
+}
+
+/**
+ * locking_get_offset - get current and max 'file' offsets for VFS
+ * @rchan: the channel
+ * @max_offset: maximum channel offset
+ *
+ * Returns the current and maximum buffer offsets in VFS terms.
+ */
+u32
+locking_get_offset(struct rchan *rchan,
+ u32 *max_offset)
+{
+ if (max_offset)
+ *max_offset = rchan->buf_size * rchan->n_bufs - 1;
+
+ return cur_write_pos(rchan) - rchan->buf;
+}
+
+/**
+ * copy_split - helper function used to copy to expanded buffer
+ *
+ * Copies the contents of the current relay channel buffer into the
+ * new channel buffer, splitting them at old_cur_idx, the bottom
+ * half of the old buffer going to the bottom of the new, likewise
+ * for the top half.
+ */
+static void
+copy_split(struct rchan *rchan, int newsize, int oldsize, char * oldbuf, u32 old_cur_idx, u32 old_buf_size)
+{
+ u32 old_cur_bufno;
+ int ge = 0, le = 0, delta;
+
+ old_cur_bufno = old_cur_idx / old_buf_size;
+
+ if (old_cur_idx >= old_buf_size) {
+ memcpy(rchan->buf, oldbuf, old_buf_size - rchan->unused_bytes[0]);
+ memcpy(rchan->buf + old_buf_size - rchan->unused_bytes[0],
+ oldbuf + old_buf_size, old_cur_idx - old_buf_size);
+
+ ge = old_buf_size;
+ le = old_cur_idx;
+ delta = -rchan->unused_bytes[0];
+ rchan->callbacks->resize_offset(rchan->id, ge, le, delta);
+
+ memcpy(rchan->buf + newsize - (oldsize - old_cur_idx),
+ oldbuf + old_cur_idx, oldsize - old_cur_idx);
+
+ ge = old_cur_idx;
+ le = oldsize - 1;
+ delta = newsize - oldsize;
+ rchan->callbacks->resize_offset(rchan->id, ge, le, delta);
+
+ cur_write_pos(rchan) = rchan->buf + old_cur_idx - rchan->unused_bytes[0];
+ rchan->unused_bytes[0] = 0;
+ } else {
+ memcpy(rchan->buf, oldbuf, old_cur_idx);
+ memcpy(rchan->buf + newsize - old_buf_size,
+ oldbuf + old_buf_size, old_buf_size);
+
+ ge = old_buf_size;
+ le = oldsize - 1;
+ delta = newsize - oldsize;
+ rchan->callbacks->resize_offset(rchan->id, ge, le, delta);
+
+ memcpy(rchan->buf + newsize - oldsize + rchan->unused_bytes[0],
+ oldbuf + old_cur_idx, old_buf_size - old_cur_idx);
+
+ ge = old_cur_idx;
+ le = old_buf_size - 1;
+ delta = newsize - oldsize + rchan->unused_bytes[0];
+ rchan->callbacks->resize_offset(rchan->id, ge, le, delta);
+
+ cur_write_pos(rchan) = rchan->buf + old_cur_idx;
+ rchan->unused_bytes[0] = 0;
+ }
+}
+
+/**
+ * copy_expand - copies old buffer to larger buffer
+ * @rchan: the channel
+ * @newsize: the size of the new buffer
+ * @oldsize: the size of the old buffer
+ * @oldsize: the old buffer
+ * @old_cur_idx: the current index into the old buffer
+ * @old_buf_size: the old buffer's sub-buffer size
+ *
+ * Copies the contents of the old relay channel buffer into the
+ * new channel buffer.
+ */
+void
+copy_expand(struct rchan *rchan, int newsize, int oldsize, char * oldbuf, u32 old_cur_idx, u32 old_buf_size)
+{
+ u32 total_bytes;
+ u32 cur_idx;
+
+ copy_split(rchan, newsize, oldsize, oldbuf, old_cur_idx, old_buf_size);
+
+ total_bytes = rchan->bufs_produced * old_buf_size +
+ bytes_produced(rchan) + old_cur_idx;
+
+ if (old_cur_idx > old_buf_size)
+ total_bytes -= old_buf_size;
+
+ cur_idx = cur_write_pos(rchan) - rchan->buf;
+
+ if (cur_idx >= rchan->buf_size)
+ total_bytes -= (cur_idx - rchan->buf_size);
+ else
+ total_bytes -= cur_idx;
+ rchan->bufs_produced = total_bytes / rchan->buf_size;
+ bytes_produced(rchan) = total_bytes % rchan->buf_size;
+
+ total_bytes = rchan->bufs_consumed * old_buf_size +
+ rchan->bytes_consumed;
+ rchan->bufs_consumed = total_bytes / rchan->buf_size;
+ rchan->bytes_consumed = total_bytes % rchan->buf_size;
+
+ if (rchan->buf_id % 2)
+ rchan->buf_id++;
+}
+
+/**
+ * copy_from_curbuf - helper function used to copy to shrunken buffer
+ *
+ * Copies the contents of the current relay channel sub-buffer into the
+ * new channel buffer.
+ */
+static u32
+copy_from_curbuf(struct rchan *rchan, u32 old_cur_idx, u32 old_buf_size, int newsize, char *oldbuf)
+{
+ u32 old_cur_bufno;
+ u32 copy_bytes;
+ char *copy_to;
+ char *copy_from;
+ int ge = 0, le = 0, delta;
+
+ old_cur_bufno = old_cur_idx / old_buf_size;
+ copy_bytes = old_cur_idx;
+
+ if (old_cur_idx >= old_buf_size) {
+ copy_bytes -= old_buf_size;
+ if (copy_bytes > newsize)
+ copy_bytes = newsize;
+
+ delta = -(old_buf_size - newsize) - old_cur_idx;
+ } else {
+ copy_bytes = old_cur_idx;
+ if (copy_bytes > newsize) {
+ copy_bytes = newsize;
+ delta = -(old_buf_size - (newsize +
+ (old_buf_size - old_cur_idx)));
+ } else
+ delta = newsize - copy_bytes;
+ }
+
+ ge = old_cur_idx - copy_bytes;
+ le = old_cur_idx;
+
+ copy_to = rchan->buf + newsize - copy_bytes;
+ copy_from = oldbuf + old_cur_idx - copy_bytes;
+
+ memcpy(copy_to, copy_from, copy_bytes);
+ rchan->callbacks->resize_offset(rchan->id, ge, le, delta);
+
+ return copy_bytes;
+}
+
+/**
+ * copy_from_otherbuf - helper function used to copy to shrunken buffer
+ *
+ * Copies the contents of the non-current relay channel sub-buffer into
+ * the new channel buffer.
+ */
+static void
+copy_from_otherbuf(struct rchan *rchan, u32 old_cur_idx, u32 old_buf_size, int oldsize, int newsize, char *copy_to, u32 copied_bytes, char *oldbuf)
+{
+ char *copy_from;
+ int ge = 0, le = 0, delta;
+ u32 copy_bytes = newsize - copied_bytes;
+
+ if (old_cur_idx >= old_buf_size) {
+ copy_from = oldbuf + old_buf_size -
+ rchan->unused_bytes[0] - copy_bytes;
+ delta = -(old_buf_size - newsize + copied_bytes -
+ rchan->unused_bytes[0]);
+ ge = old_buf_size - copy_bytes - rchan->unused_bytes[0];
+ le = old_buf_size;
+ } else {
+ copy_from = oldbuf + oldsize -
+ rchan->unused_bytes[1] - copy_bytes;
+ delta = -(oldsize - newsize + copied_bytes -
+ rchan->unused_bytes[1]);
+ ge = oldsize - copy_bytes - rchan->unused_bytes[1];
+ le = oldsize;
+ }
+
+ memcpy(copy_to, copy_from, copy_bytes);
+ rchan->callbacks->resize_offset(rchan->id, ge, le, delta);
+}
+
+/**
+ * copy_shrink - copies old buffer to smaller buffer
+ * @rchan: the channel
+ * @newsize: the size of the new buffer
+ * @oldsize: the size of the old buffer
+ * @oldsize: the old buffer
+ * @old_cur_idx: the current index into the old buffer
+ * @old_buf_size: the old buffer's sub-buffer size
+ *
+ * Copies the contents of the old relay channel buffer into the
+ * new channel buffer.
+ */
+void
+copy_shrink(struct rchan *rchan, int newsize, int oldsize, char *oldbuf, u32 old_cur_idx, u32 old_buf_size)
+{
+ u32 copy_bytes;
+ char *copy_to;
+ u32 total_bytes;
+
+ copy_bytes = copy_from_curbuf(rchan, old_cur_idx, old_buf_size,
+ newsize, oldbuf);
+
+ copy_to = rchan->buf + newsize - copy_bytes;
+ copy_bytes = newsize - copy_bytes;
+ if (copy_bytes) {
+ copy_to -= copy_bytes;
+ copy_from_otherbuf(rchan, old_cur_idx, old_buf_size, oldsize,
+ newsize, copy_to, copy_bytes, oldbuf);
+ }
+
+ cur_write_pos(rchan) = rchan->buf;
+ rchan->unused_bytes[0] = 0;
+ rchan->unused_bytes[1] = 0;
+
+ total_bytes = rchan->bufs_produced * old_buf_size +
+ bytes_produced(rchan) + old_cur_idx;
+
+ if (old_cur_idx > old_buf_size)
+ total_bytes -= old_buf_size;
+
+ rchan->bufs_produced = total_bytes / rchan->buf_size;
+ bytes_produced(rchan) = total_bytes % rchan->buf_size;
+
+ total_bytes = rchan->bufs_consumed * old_buf_size +
+ rchan->bytes_consumed;
+ rchan->bufs_consumed = total_bytes / rchan->buf_size;
+ rchan->bytes_consumed = total_bytes % rchan->buf_size;
+
+ if (rchan->buf_id % 2)
+ rchan->buf_id++;
+}
+
+/**
+ * locking_copy_contents - relayfs copy_contents() implementation
+ * @rchan: the channel
+ * @newsize: the size of the new buffer
+ * @oldsize: the size of the old buffer
+ * @oldsize: the old buffer
+ * @old_cur_idx: the current index into the old buffer
+ * @old_buf_size: the old buffer's sub-buffer size
+ * @old_n_bufs: the old buffer's sub-buffer count
+ *
+ * Copies the contents of the old relay channel buffer into the
+ * new channel buffer.
+ */
+void
+locking_copy_contents(struct rchan *rchan, int newsize, int oldsize, char * oldbuf, u32 old_cur_idx, u32 old_buf_size, u32 old_n_bufs)
+{
+ u32 old_cur_bufno;
+ old_cur_bufno = old_cur_idx / old_buf_size;
+
+ if (newsize > oldsize)
+ copy_expand(rchan, newsize, oldsize, oldbuf,
+ old_cur_idx, old_buf_size);
+ else
+ copy_shrink(rchan, newsize, oldsize, oldbuf,
+ old_cur_idx, old_buf_size);
+
+ write_buf(rchan) = rchan->buf;
+ read_buf(rchan) = rchan->buf + rchan->buf_size;
+ write_buf_end(rchan) = write_buf(rchan) + rchan->buf_size;
+ read_buf_end(rchan) = read_buf(rchan) + rchan->buf_size;
+ read_limit(rchan) = read_buf(rchan);
+ write_limit(rchan) = write_buf_end(rchan) - rchan->end_reserve;
+
+ rchan->offsets_changed = 1;
+}
+
+
+
+
+
+
+
+
diff -urpN -X dontdiff linux-2.6.0-test1/fs/relayfs/relay_locking.h linux-2.6.0-test1-relayfs-printk/fs/relayfs/relay_locking.h
--- linux-2.6.0-test1/fs/relayfs/relay_locking.h Wed Dec 31 18:00:00 1969
+++ linux-2.6.0-test1-relayfs-printk/fs/relayfs/relay_locking.h Sun Jul 13 22:32:49 2003
@@ -0,0 +1,39 @@
+#ifndef _RELAY_LOCKING_H
+#define _RELAY_LOCKING_H
+
+#define RESIZE_THRESHOLD_LOCKING 1 / 3
+
+extern char *
+locking_reserve(struct rchan *rchan,
+ u32 slot_len,
+ struct timeval *time_stamp,
+ u32 *tsc,
+ int *err,
+ int *interrupting);
+
+extern void
+locking_commit(struct rchan *rchan,
+ char *from,
+ u32 len,
+ int deliver,
+ int interrupting);
+
+extern void
+locking_resume(struct rchan *rchan);
+
+extern void
+locking_finalize(struct rchan *rchan);
+
+extern u32
+locking_get_offset(struct rchan *rchan, u32 *max_offset);
+
+extern void
+locking_copy_contents(struct rchan *rchan,
+ int newsize,
+ int oldsize,
+ char * oldbuf,
+ u32 old_cur_idx,
+ u32 old_buf_size,
+ u32 old_n_bufs);
+
+#endif /* _RELAY_LOCKING_H */
diff -urpN -X dontdiff linux-2.6.0-test1/fs/relayfs/relay_lockless.c linux-2.6.0-test1-relayfs-printk/fs/relayfs/relay_lockless.c
--- linux-2.6.0-test1/fs/relayfs/relay_lockless.c Wed Dec 31 18:00:00 1969
+++ linux-2.6.0-test1-relayfs-printk/fs/relayfs/relay_lockless.c Sun Jul 13 22:32:49 2003
@@ -0,0 +1,905 @@
+/*
+ * RelayFS lockless scheme implementation.
+ *
+ * Copyright (C) 1999, 2000, 2001, 2002 - Karim Yaghmour (karim@opersys.com)
+ * Copyright (C) 2002, 2003 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
+ * Copyright (C) 2002, 2003 - Bob Wisniewski (bob@watson.ibm.com), IBM Corp
+ *
+ * This file is released under the GPL.
+ */
+
+#include <asm/relay.h>
+#include "relay_lockless.h"
+
+/**
+ * compare_and_store_volatile - self-explicit
+ * @ptr: ptr to the word that will receive the new value
+ * @oval: the value we think is currently in *ptr
+ * @nval: the value *ptr will get if we were right
+ */
+inline int
+compare_and_store_volatile(volatile u32 *ptr,
+ u32 oval,
+ u32 nval)
+{
+ u32 prev;
+
+ barrier();
+ prev = cmpxchg(ptr, oval, nval);
+ barrier();
+
+ return (prev == oval);
+}
+
+/**
+ * atomic_set_volatile - atomically set the value in ptr to nval.
+ * @ptr: ptr to the word that will receive the new value
+ * @nval: the new value
+ */
+inline void
+atomic_set_volatile(atomic_t *ptr,
+ u32 nval)
+{
+ barrier();
+ atomic_set(ptr, (int)nval);
+ barrier();
+}
+
+/**
+ * atomic_add_volatile - atomically add val to the value at ptr.
+ * @ptr: ptr to the word that will receive the addition
+ * @val: the value to add to *ptr
+ */
+inline void
+atomic_add_volatile(atomic_t *ptr, u32 val)
+{
+ barrier();
+ atomic_add((int)val, ptr);
+ barrier();
+}
+
+/**
+ * atomic_sub_volatile - atomically substract val from the value at ptr.
+ * @ptr: ptr to the word that will receive the subtraction
+ * @val: the value to subtract from *ptr
+ */
+inline void
+atomic_sub_volatile(atomic_t *ptr, s32 val)
+{
+ barrier();
+ atomic_sub((int)val, ptr);
+ barrier();
+}
+
+/**
+ * expand_check - check whether the channel needs expanding
+ * @rchan: the channel
+ * @active_bufs: the number of unread sub-buffers
+ *
+ * See resize_check() for details.
+ *
+ * Returns the suggested number of sub-buffers for the new
+ * buffer.
+ */
+static inline u32
+expand_check(struct rchan *rchan, u32 active_bufs)
+{
+ u32 new_n_bufs = 0;
+
+ if (rchan->resize_max && !rchan->mapped &&
+ active_bufs == (rchan->n_bufs * RESIZE_THRESHOLD_LOCKLESS)) {
+ new_n_bufs = rchan->n_bufs * 2;
+ }
+
+ return new_n_bufs;
+}
+
+/**
+ * shrink_check - check whether the channel needs shrinking
+ * @rchan: the channel
+ * @active_bufs: the number of unread sub-buffers
+ *
+ * See resize_check() for details.
+ *
+ * Returns the suggested number of sub-buffers for the new
+ * buffer.
+ */
+static inline u32
+shrink_check(struct rchan *rchan, u32 active_bufs)
+{
+ u32 needed_bufsize, n;
+ struct timeval ts;
+ u32 low_water_time;
+ u32 new_n_bufs = 0;
+
+ if (rchan->resize_min == 0 || rchan->mapped ||
+ rchan->resize_min >= rchan->n_bufs * rchan->buf_size)
+ goto out;
+
+ if (active_bufs > rchan->n_bufs * RESIZE_THRESHOLD_LOCKLESS) {
+ do_gettimeofday(&rchan->low_water_time);
+ goto out;
+ }
+
+ do_gettimeofday(&ts);
+ low_water_time = calc_time_delta(&ts, &rchan->low_water_time);
+ if (low_water_time > LOW_WATER_TIME) {
+ needed_bufsize = active_bufs * rchan->buf_size;
+ for (n = 4; n < rchan->n_bufs; n *= 2) {
+ if ((n * rchan->buf_size >= rchan->resize_min) &&
+ (n * rchan->buf_size <= rchan->resize_max) &&
+ (n * (rchan->buf_size * RESIZE_THRESHOLD_LOCKLESS) > needed_bufsize))
+ break;
+ }
+
+ if (n >= rchan->n_bufs || n < 4)
+ goto out;
+
+ new_n_bufs = n;
+ }
+
+out:
+ return new_n_bufs;
+}
+
+/**
+ * resize_check - check whether the channel needs resizing
+ * @rchan: the channel
+ *
+ * If the channel is above 3/4 full, it will be doubled in
+ * size. If a minute has passed since the last resize, and
+ * it's no longer full, it will be shrunk to whatever size
+ * will comfortably fit the contents.
+ */
+static void
+resize_check(struct rchan *rchan)
+{
+ u32 active_bufs;
+ u32 new_n_bufs;
+ int resize_type = RELAY_RESIZE_NONE;
+
+ if (rchan->resize_min == 0)
+ return;
+
+ active_bufs = rchan->bufs_produced - rchan->bufs_consumed + 1;
+
+ new_n_bufs = expand_check(rchan, active_bufs);
+ if (new_n_bufs) {
+ resize_type = RELAY_RESIZE_EXPAND;
+ }
+ else {
+ new_n_bufs = shrink_check(rchan, active_bufs);
+ if (new_n_bufs)
+ resize_type = RELAY_RESIZE_SHRINK;
+ }
+
+ if (resize_type != RELAY_RESIZE_NONE)
+ rchan->callbacks->needs_resize(rchan->id,
+ resize_type,
+ rchan->buf_size,
+ new_n_bufs);
+}
+
+/**
+ * lockless_commit - commit a reserved slot in the buffer
+ * @rchan: the channel
+ * @from: commit the length starting here
+ * @len: length committed
+ * @deliver: length committed
+ * @interrupting: not used
+ *
+ * Commits len bytes and calls deliver callback if applicable.
+ */
+inline void
+lockless_commit(struct rchan *rchan,
+ char *from,
+ u32 len,
+ int deliver,
+ int interrupting)
+{
+ u32 bufno, idx;
+
+ idx = from - rchan->buf;
+
+ if (len > 0) {
+ bufno = RELAY_BUFNO_GET(idx, offset_bits(rchan));
+ atomic_add_volatile(&fill_count(rchan, bufno), len);
+ }
+
+ if (deliver) {
+ rchan->callbacks->deliver(rchan->id, from, len);
+ resize_check(rchan);
+ }
+}
+
+/**
+ * get_buffer_end - get the address of the end of buffer
+ * @rchan: the channel
+ * @buf_idx: index into channel corresponding to address
+ */
+static inline char *
+get_buffer_end(struct rchan *rchan, u32 buf_idx)
+{
+ return rchan->buf
+ + RELAY_BUF_OFFSET_CLEAR(buf_idx, offset_mask(rchan))
+ + RELAY_BUF_SIZE(offset_bits(rchan));
+}
+
+/**
+ * finalize_buffer - utility function consolidating end-of-buffer tasks.
+ * @end_idx: index into trace buffer to write the end-buffer event at
+ * @size_lost: number of unused bytes at the end of the buffer
+ * @time_stamp: the time of the end-buffer event
+ * @tsc: the timestamp counter associated with time
+ * @cpu_id: the CPU id associated with the event
+ *
+ * This function must be called with local irqs disabled.
+ */
+static inline void
+finalize_buffer(u32 end_idx,
+ u32 size_lost,
+ struct timeval *time_stamp,
+ u32 *tsc,
+ struct rchan *rchan)
+{
+ char* cur_write_pos;
+ char* write_buf_end;
+ u32 bufno;
+ int bytes_written;
+
+ cur_write_pos = rchan->buf + end_idx;
+ write_buf_end = get_buffer_end(rchan, end_idx - 1);
+
+ bytes_written = rchan->callbacks->buffer_end(rchan->id, cur_write_pos,
+ write_buf_end, *time_stamp, *tsc, using_tsc(rchan));
+ /* We assume that since the client didn't write anything, at some
+ point the unused_bytes value will be needed. */
+ if (bytes_written == 0)
+ rchan->unused_bytes[rchan->buf_id % rchan->n_bufs] = size_lost;
+
+ bufno = RELAY_BUFNO_GET(end_idx, offset_bits(rchan));
+ atomic_add_volatile(&fill_count(rchan, bufno), size_lost);
+ rchan->bufs_produced++;
+}
+
+/**
+ * lockless_finalize: - finalize last buffer at end of channel use
+ * @rchan: the channel
+ */
+inline void
+lockless_finalize(struct rchan *rchan)
+{
+ u32 event_end_idx;
+ u32 size_lost;
+ unsigned long int flags;
+ struct timeval time;
+ u32 tsc;
+
+ event_end_idx = RELAY_BUF_OFFSET_GET(idx(rchan), offset_mask(rchan));
+ size_lost = RELAY_BUF_SIZE(offset_bits(rchan)) - event_end_idx;
+
+ local_irq_save(flags);
+ get_timestamp(&time, &tsc, rchan);
+ finalize_buffer(idx(rchan) & idx_mask(rchan), size_lost,
+ &time, &tsc, rchan);
+ local_irq_restore(flags);
+}
+
+/**
+ * discard_check: - determine whether a write should be discarded
+ * @rchan: the channel
+ * @old_idx: index into trace buffer where check for space should begin
+ * @write_len: the length of the write to check
+ * @time_stamp: the time of the end-buffer event
+ * @tsc: the timestamp counter associated with time
+ *
+ * The return value contains the result flags and is an ORed combination
+ * of the following:
+ *
+ * RELAY_WRITE_DISCARD_NONE - write should not be discarded
+ * RELAY_BUFFER_SWITCH - buffer switch occurred
+ * RELAY_WRITE_DISCARD - write should be discarded (all buffers are full)
+ * RELAY_WRITE_TOO_LONG - write won't fit into even an empty buffer
+ */
+static inline int
+discard_check(struct rchan *rchan,
+ u32 old_idx,
+ u32 write_len,
+ struct timeval *time_stamp,
+ u32 *tsc)
+{
+ u32 buffers_ready;
+ u32 offset_mask = offset_mask(rchan);
+ u8 offset_bits = offset_bits(rchan);
+ u32 idx_mask = idx_mask(rchan);
+ u32 size_lost;
+ unsigned long int flags;
+
+ if (write_len > RELAY_BUF_SIZE(offset_bits)) {
+ rchan->events_lost++;
+ return RELAY_WRITE_DISCARD | RELAY_WRITE_TOO_LONG;
+ }
+
+ local_irq_save(flags);
+
+ if (atomic_read(&rchan->suspended) == 1) {
+ local_irq_restore(flags);
+ rchan->events_lost++;
+ return RELAY_WRITE_DISCARD;
+ }
+
+ buffers_ready = rchan->bufs_produced - rchan->bufs_consumed;
+ if (buffers_ready == rchan->n_bufs - 1) {
+ if (rchan->callbacks->buffers_full(rchan->id)) {
+ atomic_set(&rchan->suspended, 1);
+ get_timestamp(time_stamp, tsc, rchan);
+ size_lost = RELAY_BUF_SIZE(offset_bits)
+ - RELAY_BUF_OFFSET_GET(old_idx, offset_mask);
+ finalize_buffer(old_idx & idx_mask, size_lost,
+ time_stamp, tsc, rchan);
+
+ last_event_index(rchan) = old_idx;
+ last_event_timestamp(rchan) = *time_stamp;
+ last_event_tsc(rchan) = *tsc;
+
+ local_irq_restore(flags);
+
+ rchan->events_lost++;
+
+ return RELAY_BUFFER_SWITCH | RELAY_WRITE_DISCARD;
+ }
+ }
+
+ local_irq_restore(flags);
+
+ return RELAY_WRITE_DISCARD_NONE;
+}
+
+/**
+ * switch_buffers - switch over to a new sub-buffer
+ * @rchan: the channel
+ * @slot_len: the length of the slot needed for the current write
+ * @offset: the offset calculated for the new index
+ * @ts: timestamp
+ * @tsc: the timestamp counter associated with time
+ * @old_idx: the value of the buffer control index when we were called
+ * @old_idx: the new calculated value of the buffer control index
+ */
+static inline void
+switch_buffers(struct rchan *rchan,
+ u32 slot_len,
+ u32 offset,
+ struct timeval *ts,
+ u32 *tsc,
+ u32 new_idx,
+ u32 old_idx)
+{
+ u32 size_lost = rchan->end_reserve;
+ unsigned long int flags;
+ u32 idx_mask = idx_mask(rchan);
+ u8 offset_bits = offset_bits(rchan);
+ char *cur_write_pos;
+ u32 new_buf_no;
+ u32 start_reserve = rchan->start_reserve;
+
+ if (offset > 0)
+ size_lost += slot_len - offset;
+ else
+ old_idx += slot_len;
+
+ local_irq_save(flags);
+ finalize_buffer(old_idx & idx_mask, size_lost,
+ ts, tsc, rchan);
+ rchan->buf_start_time = *ts;
+ rchan->buf_start_tsc = *tsc;
+
+ local_irq_restore(flags);
+
+ cur_write_pos = rchan->buf + RELAY_BUF_OFFSET_CLEAR((new_idx
+ & idx_mask), offset_mask(rchan));
+
+ rchan->buf_id++;
+
+ rchan->unused_bytes[rchan->buf_id % rchan->n_bufs] = 0;
+
+ rchan->callbacks->buffer_start(rchan->id, cur_write_pos,
+ rchan->buf_id, *ts, *tsc, using_tsc(rchan));
+
+ new_buf_no = RELAY_BUFNO_GET(new_idx & idx_mask, offset_bits);
+
+ atomic_sub_volatile(&fill_count(rchan, new_buf_no),
+ RELAY_BUF_SIZE(offset_bits) - start_reserve);
+
+ if (atomic_read(&fill_count(rchan, new_buf_no)) < start_reserve)
+ atomic_set_volatile(&fill_count(rchan, new_buf_no),
+ start_reserve);
+}
+
+/**
+ * lockless_reserve_slow - the slow reserve path in the lockless scheme
+ * @rchan: the channel
+ * @slot_len: the length of the slot to reserve
+ * @ts: variable that will receive the time the slot was reserved
+ * @tsc: the timestamp counter associated with time
+ * @old_idx: the value of the buffer control index when we were called
+ * @err: receives the result flags
+ *
+ * Returns pointer to the beginning of the reserved slot, NULL if error.
+
+ * err values same as for lockless_reserve.
+ */
+static inline char *
+lockless_reserve_slow(struct rchan *rchan,
+ u32 slot_len,
+ struct timeval *ts,
+ u32 *tsc,
+ u32 old_idx,
+ int *err)
+{
+ u32 new_idx, offset;
+ unsigned long int flags;
+ u32 offset_mask = offset_mask(rchan);
+ u32 idx_mask = idx_mask(rchan);
+ u32 start_reserve = rchan->start_reserve;
+ u32 end_reserve = rchan->end_reserve;
+ int discard_event;
+ u32 reserved_idx;
+ char *cur_write_pos;
+ int initializing = 0;
+
+ *err = RELAY_BUFFER_SWITCH_NONE;
+
+ discard_event = discard_check(rchan, old_idx, slot_len, ts, tsc);
+ if (discard_event != RELAY_WRITE_DISCARD_NONE) {
+ *err = discard_event;
+ return NULL;
+ }
+
+ local_irq_save(flags);
+ if (rchan->initialized == 0) {
+ rchan->initialized = initializing = 1;
+ idx(rchan) = rchan->start_reserve + rchan->rchan_start_reserve;
+ }
+ local_irq_restore(flags);
+
+ do {
+ old_idx = idx(rchan);
+ new_idx = old_idx + slot_len;
+
+ offset = RELAY_BUF_OFFSET_GET(new_idx + end_reserve,
+ offset_mask);
+
+ if ((offset < slot_len) && (offset > 0)) {
+ reserved_idx = RELAY_BUF_OFFSET_CLEAR(new_idx
+ + end_reserve, offset_mask) + start_reserve;
+ new_idx = reserved_idx + slot_len;
+ } else if (offset < slot_len) {
+ reserved_idx = old_idx;
+ new_idx = RELAY_BUF_OFFSET_CLEAR(new_idx
+ + end_reserve, offset_mask) + start_reserve;
+ } else
+ reserved_idx = old_idx;
+
+ get_timestamp(ts, tsc, rchan);
+ } while (!compare_and_store_volatile(&idx(rchan), old_idx, new_idx));
+
+ reserved_idx &= idx_mask;
+
+ if (initializing == 1) {
+ cur_write_pos = rchan->buf
+ + RELAY_BUF_OFFSET_CLEAR((old_idx & idx_mask),
+ offset_mask(rchan));
+ rchan->buf_start_time = *ts;
+ rchan->buf_start_tsc = *tsc;
+ rchan->unused_bytes[0] = 0;
+
+ rchan->callbacks->buffer_start(rchan->id, cur_write_pos,
+ rchan->buf_id, *ts, *tsc, using_tsc(rchan));
+ }
+
+ if (offset < slot_len) {
+ switch_buffers(rchan, slot_len, offset, ts, tsc, new_idx,
+ old_idx);
+ *err = RELAY_BUFFER_SWITCH;
+ }
+
+ /* If not using TSC, need to calc time delta */
+ recalc_time_delta(ts, tsc, rchan);
+
+ return rchan->buf + reserved_idx;
+}
+
+/**
+ * lockless_reserve - reserve a slot in the trace buffer for an event.
+ * @rchan: the channel
+ * @slot_len: the length of the slot to reserve
+ * @ts: variable that will receive the time the slot was reserved
+ * @tsc: the timestamp counter associated with time
+ * @err: receives the result flags
+ * @interrupting: not used
+ *
+ * Returns pointer to the beginning of the reserved slot, NULL if error.
+ *
+ * The err value contains the result flags and is an ORed combination
+ * of the following:
+ *
+ * RELAY_BUFFER_SWITCH_NONE - no buffer switch occurred
+ * RELAY_EVENT_DISCARD_NONE - event should not be discarded
+ * RELAY_BUFFER_SWITCH - buffer switch occurred
+ * RELAY_EVENT_DISCARD - event should be discarded (all buffers are full)
+ * RELAY_EVENT_TOO_LONG - event won't fit into even an empty buffer
+ */
+inline char *
+lockless_reserve(struct rchan *rchan,
+ u32 slot_len,
+ struct timeval *ts,
+ u32 *tsc,
+ int *err,
+ int *interrupting)
+{
+ u32 old_idx, new_idx, offset;
+ u32 offset_mask = offset_mask(rchan);
+
+ do {
+ old_idx = idx(rchan);
+ new_idx = old_idx + slot_len;
+
+ offset = RELAY_BUF_OFFSET_GET(new_idx + rchan->end_reserve,
+ offset_mask);
+
+ if (offset < slot_len)
+ return lockless_reserve_slow(rchan, slot_len,
+ ts, tsc, old_idx, err);
+
+ get_time_or_tsc(ts, tsc, rchan);
+ } while (!compare_and_store_volatile(&idx(rchan), old_idx, new_idx));
+
+ /* If not using TSC, need to calc time delta */
+ recalc_time_delta(ts, tsc, rchan);
+
+ *err = RELAY_BUFFER_SWITCH_NONE;
+
+ return rchan->buf + (old_idx & idx_mask(rchan));
+}
+
+/**
+ * lockless_resume - resume a suspended channel
+ * @rchan: the channel
+ */
+inline void
+lockless_resume(struct rchan *rchan)
+{
+ int discard_size;
+ u32 last_event_buf_no;
+ u32 last_buffer_lost_size;
+ u32 last_event_offset;
+ u32 new_idx;
+ int freed_buf_no;
+ char *cur_write_pos;
+ char *write_buf_end;
+ u32 bufno;
+ u32 size_lost;
+ int bytes_written;
+
+ freed_buf_no = rchan->bufs_produced % rchan->n_bufs;
+
+ atomic_set_volatile(&fill_count(rchan, freed_buf_no),
+ rchan->start_reserve);
+
+ last_event_offset = RELAY_BUF_OFFSET_GET(last_event_index(rchan),
+ offset_mask(rchan));
+ last_event_buf_no = RELAY_BUFNO_GET(last_event_index(rchan),
+ offset_bits(rchan));
+ last_buffer_lost_size = RELAY_BUF_SIZE(offset_bits(rchan))
+ - last_event_offset;
+
+ discard_size = atomic_read(&fill_count(rchan, last_event_buf_no))
+ - last_event_offset - last_buffer_lost_size;
+ if (discard_size > 0)
+ atomic_sub_volatile(&fill_count(rchan, last_event_buf_no),
+ discard_size);
+
+ cur_write_pos = rchan->buf
+ + (last_event_index(rchan) & idx_mask(rchan));
+
+ write_buf_end = get_buffer_end(rchan, last_event_index(rchan) - 1);
+ size_lost = write_buf_end - cur_write_pos;
+
+ bytes_written = rchan->callbacks->buffer_end(rchan->id,
+ cur_write_pos,
+ write_buf_end,
+ last_event_timestamp(rchan),
+ last_event_tsc(rchan),
+ using_tsc(rchan));
+ /* We assume that since the client didn't write anything, at some
+ point the unused_bytes value will be needed. */
+ if (bytes_written == 0)
+ rchan->unused_bytes[rchan->buf_id % rchan->n_bufs] = size_lost;
+
+ bufno = RELAY_BUFNO_GET(last_event_index(rchan), offset_bits(rchan));
+ atomic_add_volatile(&fill_count(rchan, bufno), size_lost);
+
+ get_timestamp(&rchan->buf_start_time, &rchan->buf_start_tsc, rchan);
+
+ new_idx = idx(rchan) + RELAY_BUF_SIZE(offset_bits(rchan));
+ new_idx = RELAY_BUF_OFFSET_CLEAR(new_idx,
+ offset_mask(rchan)) + rchan->start_reserve;
+
+ cur_write_pos = rchan->buf
+ + RELAY_BUF_OFFSET_CLEAR((new_idx & idx_mask(rchan)),
+ offset_mask(rchan));
+
+ rchan->buf_id++;
+ rchan->unused_bytes[rchan->buf_id % rchan->n_bufs] = 0;
+
+ rchan->callbacks->buffer_start(rchan->id,
+ cur_write_pos,
+ rchan->buf_id,
+ rchan->buf_start_time,
+ rchan->buf_start_tsc,
+ using_tsc(rchan));
+
+ bufno = RELAY_BUFNO_GET(new_idx & idx_mask(rchan),
+ offset_bits(rchan));
+
+ atomic_sub_volatile(&fill_count(rchan, bufno),
+ RELAY_BUF_SIZE(offset_bits(rchan)) - rchan->start_reserve);
+
+ if (atomic_read(&fill_count(rchan, bufno)) < rchan->start_reserve)
+ atomic_set_volatile(&fill_count(rchan, bufno),
+ rchan->start_reserve);
+
+ idx(rchan) = new_idx;
+
+ atomic_set(&rchan->suspended, 0);
+}
+
+/**
+ * lockless_get_offset - get current and max 'file' offsets for VFS
+ * @rchan: the channel
+ * @max_offset: maximum channel offset
+ *
+ * Returns the current and maximum buffer offsets in VFS terms.
+ */
+u32
+lockless_get_offset(struct rchan *rchan,
+ u32 *max_offset)
+{
+ if (max_offset)
+ *max_offset = rchan->buf_size * rchan->n_bufs - 1;
+
+ return idx(rchan) & idx_mask(rchan);
+}
+
+/**
+ * copy_expand - copies old buffer to larger buffer
+ * @rchan: the channel
+ * @newsize: the size of the new buffer
+ * @oldsize: the size of the old buffer
+ * @oldsize: the old buffer
+ * @old_cur_idx: the current index into the old buffer
+ * @old_buf_size: the old buffer's sub-buffer size
+ *
+ * Copies the contents of the current relay channel buffer into the
+ * new channel buffer, splitting them at old_cur_idx, the bottom
+ * half of the old buffer going to the bottom of the new, likewise
+ * for the top half.
+ */
+static void
+copy_expand(struct rchan *rchan, int newsize, int oldsize, char * oldbuf, u32 old_cur_idx, u32 old_buf_size, u32 old_n_bufs)
+{
+ char *copy_first, *copy_last = NULL;
+ u32 copy_first_size = 0, copy_last_size = 0;
+ u32 new_cur_idx = 0, newbufs;
+ int old_cur_bufno, new_cur_bufno, delta, i;
+ u32 ge, le;
+
+ new_cur_idx = relay_get_offset(rchan, NULL) & idx_mask(rchan);
+ old_cur_bufno = old_cur_idx / old_buf_size;
+ new_cur_bufno = new_cur_idx / rchan->buf_size;
+
+ copy_first = oldbuf;
+ copy_first_size = (old_cur_bufno + 1) * old_buf_size;
+ memcpy(rchan->buf, copy_first, copy_first_size);
+
+ copy_last = copy_first + copy_first_size;
+ copy_last_size = oldsize - copy_first_size;
+ memcpy(rchan->buf + copy_first_size + newsize - oldsize,
+ copy_last, copy_last_size);
+
+ memset(rchan->buf + copy_first_size, 0, newsize - oldsize);
+
+ newbufs = (newsize - oldsize) / rchan->buf_size;
+ for (i = old_cur_bufno + 1; i < old_n_bufs; i++) {
+ atomic_set(&fill_count(rchan, i + newbufs), atomic_read(&fill_count(rchan, i)));
+ rchan->unused_bytes[i + newbufs] = rchan->unused_bytes[i];
+ }
+ for (i = old_cur_bufno + 1; i < old_cur_bufno + newbufs + 1; i++) {
+ atomic_set(&fill_count(rchan, i),
+ (int)RELAY_BUF_SIZE(offset_bits(rchan)));
+ rchan->unused_bytes[i] = 0;
+ }
+
+ rchan->buf_id = new_cur_bufno;
+
+ delta = newsize - oldsize;
+ ge = (old_cur_bufno + 1) * old_buf_size;
+ le = oldsize;
+ rchan->callbacks->resize_offset(rchan->id, ge, le, delta);
+
+ rchan->offsets_changed = 1;
+}
+
+/* Used only for buffer shrinking */
+static int tmp_unused[RELAY_MAX_BUFS];
+static atomic_t tmp_fill[RELAY_MAX_BUFS];
+
+/**
+ * copy_to_bottom - helper function used to copy to shrunken buffer
+ *
+ * Copies the contents of the current relay channel sub-buffer into
+ * the bottom of the new channel buffer.
+
+ * Returns the change in position of the new sub-buffer.
+ */
+static int
+copy_to_bottom(struct rchan *rchan, char * oldbuf, u32 old_buf_size, int old_cur_bufno, int new_cur_bufno)
+{
+ int delta;
+ u32 ge, le;
+
+ memcpy(rchan->buf + new_cur_bufno * old_buf_size,
+ oldbuf + old_cur_bufno * old_buf_size, old_buf_size);
+ atomic_set(&fill_count(rchan, new_cur_bufno),
+ atomic_read(&tmp_fill[old_cur_bufno]));
+ rchan->unused_bytes[new_cur_bufno] = tmp_unused[old_cur_bufno];
+
+ ge = old_cur_bufno * old_buf_size;
+ le = (old_cur_bufno + 1) * old_buf_size;
+ delta = -(old_cur_bufno * old_buf_size);
+ if (old_cur_bufno != 0) {
+ rchan->callbacks->resize_offset(rchan->id, ge, le, delta);
+ rchan->offsets_changed = 1;
+ }
+
+ return delta;
+}
+
+/**
+ * copy_rest - helper function used to copy to shrunken buffer
+ *
+ * Copies the the contents of the rest of the relay channel sub-buffers
+ * not already copied, into the remainder of the new channel buffer.
+ */
+static void
+copy_rest(struct rchan *rchan, char * oldbuf, u32 old_buf_size, u32 old_n_bufs, int old_cur_bufno, int new_cur_bufno, int copy_n_bufs)
+{
+ int delta = 0, i;
+ u32 ge, le;
+
+ le = (old_cur_bufno + 1) * old_buf_size;
+ ge = le;
+
+ for (i = 0; i < copy_n_bufs; i++, --old_cur_bufno, --new_cur_bufno) {
+ if (old_cur_bufno < 0) {
+ if (le != ge) {
+ old_cur_bufno = old_n_bufs - 1;
+ rchan->callbacks->resize_offset(rchan->id,
+ ge, le, delta);
+ rchan->offsets_changed = 1;
+ le = (old_cur_bufno + 1) * old_buf_size;
+ ge = le;
+ }
+ }
+
+ memcpy(rchan->buf + new_cur_bufno * old_buf_size,
+ oldbuf + old_cur_bufno * old_buf_size, old_buf_size);
+ atomic_set(&fill_count(rchan, new_cur_bufno),
+ atomic_read(&tmp_fill[old_cur_bufno]));
+ rchan->unused_bytes[new_cur_bufno] = tmp_unused[old_cur_bufno];
+
+ ge -= old_buf_size;
+ if (old_cur_bufno >= new_cur_bufno)
+ delta = -(old_cur_bufno - new_cur_bufno);
+ else
+ delta = new_cur_bufno - old_cur_bufno;
+
+ delta *= old_buf_size;
+ }
+
+ if (le != ge) {
+ rchan->callbacks->resize_offset(rchan->id, ge, le, delta);
+ rchan->offsets_changed = 1;
+ }
+}
+
+/**
+ * copy_shrink - copies old buffer to smaller buffer
+ * @rchan: the channel
+ * @newsize: the size of the new buffer
+ * @oldsize: the size of the old buffer
+ * @oldsize: the old buffer
+ * @old_cur_idx: the current index into the old buffer
+ * @old_buf_size: the old buffer's sub-buffer size
+ * @old_n_buf: the old buffer's sub-buffer count
+ *
+ * Copies the contents of the old relay channel buffer into the
+ * new channel buffer.
+ */
+static void
+copy_shrink(struct rchan *rchan, int newsize, int oldsize, char * oldbuf, u32 old_cur_idx, u32 old_buf_size, u32 old_n_bufs)
+{
+ int old_cur_bufno, new_cur_bufno, copy_n_bufs, delta, i;
+
+ for (i = 0; i < RELAY_MAX_BUFS; i++) {
+ tmp_unused[i] = rchan->unused_bytes[i];
+ tmp_fill[i] = rchan->scheme.lockless.fill_count[i];
+ }
+
+ old_cur_bufno = old_cur_idx / old_buf_size;
+ new_cur_bufno = 0;
+
+ delta = copy_to_bottom(rchan, oldbuf, old_buf_size, old_cur_bufno, new_cur_bufno);
+ idx(rchan) += delta;
+
+ copy_n_bufs = rchan->n_bufs - 1;
+ new_cur_bufno = rchan->n_bufs - 1;
+ old_cur_bufno--;
+ if (old_cur_bufno < 0)
+ old_cur_bufno = old_n_bufs - 1;
+
+ copy_rest(rchan, oldbuf, old_buf_size, old_n_bufs, old_cur_bufno,
+ new_cur_bufno, copy_n_bufs);
+
+ rchan->buf_id = rchan->buf_id - rchan->buf_id % rchan->n_bufs;
+}
+
+/**
+ * lockless_copy_contents - relayfs copy_contents() implementation
+ * @rchan: the channel
+ * @newsize: the size of the new buffer
+ * @oldsize: the size of the old buffer
+ * @oldsize: the old buffer
+ * @old_cur_idx: the current index into the old buffer
+ * @old_buf_size: the old buffer's sub-buffer size
+ * @old_n_bufs: the old buffer's sub-buffer count
+ *
+ * Copies the contents of the old relay channel buffer into the
+ * new channel buffer.
+ */
+void
+lockless_copy_contents(struct rchan *rchan, int newsize, int oldsize, char * oldbuf, u32 old_cur_idx, u32 old_buf_size, u32 old_n_bufs)
+{
+ int i;
+
+ bufno_bits(rchan) += resize_order(rchan);
+ idx_mask(rchan) =
+ (1UL << (bufno_bits(rchan) + offset_bits(rchan))) - 1;
+ if (resize_order(rchan) > 0) {
+ for (i = rchan->n_bufs / 2; i < rchan->n_bufs; i++) {
+ atomic_set(&fill_count(rchan, i),
+ (int)RELAY_BUF_SIZE(offset_bits(rchan)));
+ rchan->unused_bytes[i] = 0;
+ }
+ }
+
+ if (newsize > oldsize)
+ copy_expand(rchan, newsize, oldsize, oldbuf,
+ old_cur_idx, old_buf_size, old_n_bufs);
+ else
+ copy_shrink(rchan, newsize, oldsize, oldbuf,
+ old_cur_idx, old_buf_size, old_n_bufs);
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
diff -urpN -X dontdiff linux-2.6.0-test1/fs/relayfs/relay_lockless.h linux-2.6.0-test1-relayfs-printk/fs/relayfs/relay_lockless.h
--- linux-2.6.0-test1/fs/relayfs/relay_lockless.h Wed Dec 31 18:00:00 1969
+++ linux-2.6.0-test1-relayfs-printk/fs/relayfs/relay_lockless.h Sun Jul 13 22:32:49 2003
@@ -0,0 +1,39 @@
+#ifndef _RELAY_LOCKLESS_H
+#define _RELAY_LOCKLESS_H
+
+#define RESIZE_THRESHOLD_LOCKLESS 3 / 4
+
+extern char *
+lockless_reserve(struct rchan *rchan,
+ u32 slot_len,
+ struct timeval *time_stamp,
+ u32 *tsc,
+ int * interrupting,
+ int * errcode);
+
+extern void
+lockless_commit(struct rchan *rchan,
+ char * from,
+ u32 len,
+ int deliver,
+ int interrupting);
+
+extern void
+lockless_resume(struct rchan *rchan);
+
+extern void
+lockless_finalize(struct rchan *rchan);
+
+u32
+lockless_get_offset(struct rchan *rchan, u32 *max_offset);
+
+extern void
+lockless_copy_contents(struct rchan *rchan,
+ int newsize,
+ int oldsize,
+ char * oldbuf,
+ u32 old_cur_idx,
+ u32 old_buf_size,
+ u32 old_n_bufs);
+
+#endif/* _RELAY_LOCKLESS_H */
--
Regards,
Tom Zanussi <zanussi@us.ibm.com>
IBM Linux Technology Center/RAS
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