e2dbd60134
tipc_printf was previously used both to construct debug traces and to append data to buffers that should be sent over netlink to the tipc-config application. A global print_buffer was used to format the string before it was copied to the actual output buffer. This could lead to concurrent access of the global print_buffer, which then had to be lock protected. This is simplified by changing tipc_printf to append data directly to the output buffer using vscnprintf. With the new implementation of tipc_printf, there is no longer any risk of concurrent access to the internal log buffer, so the lock (and the comments describing it) are no longer strictly necessary. However, there are still a few functions that do grab this lock before resizing/dumping the log buffer. We leave the lock, and these functions untouched since they will be removed with a subsequent commit that drops the deprecated log buffer handling code Signed-off-by: Erik Hugne <erik.hugne@ericsson.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
305 lines
8.8 KiB
C
305 lines
8.8 KiB
C
/*
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* net/tipc/log.c: TIPC print buffer routines for debugging
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*
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* Copyright (c) 1996-2006, Ericsson AB
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* Copyright (c) 2005-2007, Wind River Systems
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the names of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "core.h"
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#include "config.h"
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#include "log.h"
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/*
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* TIPC pre-defines the following print buffers:
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*
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* TIPC_NULL : null buffer (i.e. print nowhere)
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* TIPC_CONS : system console
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* TIPC_LOG : TIPC log buffer
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*
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* Additional user-defined print buffers are also permitted.
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*/
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static struct print_buf null_buf = { NULL, 0, NULL, 0 };
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struct print_buf *const TIPC_NULL = &null_buf;
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static struct print_buf cons_buf = { NULL, 0, NULL, 1 };
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struct print_buf *const TIPC_CONS = &cons_buf;
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static struct print_buf log_buf = { NULL, 0, NULL, 1 };
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struct print_buf *const TIPC_LOG = &log_buf;
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/*
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* Locking policy when using print buffers.
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*
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* 1) tipc_printf() uses 'print_lock' to protect against concurrent access to
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* 'print_string' when writing to a print buffer. This also protects against
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* concurrent writes to the print buffer being written to.
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*
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* 2) tipc_log_XXX() leverages the aforementioned use of 'print_lock' to
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* protect against all types of concurrent operations on their associated
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* print buffer (not just write operations).
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*
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* Note: All routines of the form tipc_printbuf_XXX() are lock-free, and rely
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* on the caller to prevent simultaneous use of the print buffer(s) being
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* manipulated.
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*/
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static DEFINE_SPINLOCK(print_lock);
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static void tipc_printbuf_move(struct print_buf *pb_to,
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struct print_buf *pb_from);
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/**
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* tipc_printbuf_init - initialize print buffer to empty
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* @pb: pointer to print buffer structure
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* @raw: pointer to character array used by print buffer
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* @size: size of character array
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*
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* Note: If the character array is too small (or absent), the print buffer
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* becomes a null device that discards anything written to it.
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*/
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void tipc_printbuf_init(struct print_buf *pb, char *raw, u32 size)
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{
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pb->buf = raw;
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pb->crs = raw;
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pb->size = size;
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pb->echo = 0;
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if (size < TIPC_PB_MIN_SIZE) {
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pb->buf = NULL;
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} else if (raw) {
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pb->buf[0] = 0;
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pb->buf[size - 1] = ~0;
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}
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}
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/**
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* tipc_printbuf_reset - reinitialize print buffer to empty state
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* @pb: pointer to print buffer structure
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*/
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static void tipc_printbuf_reset(struct print_buf *pb)
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{
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if (pb->buf) {
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pb->crs = pb->buf;
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pb->buf[0] = 0;
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pb->buf[pb->size - 1] = ~0;
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}
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}
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/**
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* tipc_printbuf_empty - test if print buffer is in empty state
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* @pb: pointer to print buffer structure
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*
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* Returns non-zero if print buffer is empty.
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*/
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static int tipc_printbuf_empty(struct print_buf *pb)
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{
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return !pb->buf || (pb->crs == pb->buf);
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}
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/**
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* tipc_printbuf_validate - check for print buffer overflow
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* @pb: pointer to print buffer structure
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*
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* Verifies that a print buffer has captured all data written to it.
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* If data has been lost, linearize buffer and prepend an error message
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*
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* Returns length of print buffer data string (including trailing NUL)
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*/
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int tipc_printbuf_validate(struct print_buf *pb)
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{
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char *err = "\n\n*** PRINT BUFFER OVERFLOW ***\n\n";
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char *cp_buf;
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struct print_buf cb;
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if (!pb->buf)
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return 0;
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if (pb->buf[pb->size - 1] == 0) {
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cp_buf = kmalloc(pb->size, GFP_ATOMIC);
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if (cp_buf) {
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tipc_printbuf_init(&cb, cp_buf, pb->size);
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tipc_printbuf_move(&cb, pb);
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tipc_printbuf_move(pb, &cb);
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kfree(cp_buf);
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memcpy(pb->buf, err, strlen(err));
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} else {
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tipc_printbuf_reset(pb);
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tipc_printf(pb, err);
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}
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}
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return pb->crs - pb->buf + 1;
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}
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/**
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* tipc_printbuf_move - move print buffer contents to another print buffer
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* @pb_to: pointer to destination print buffer structure
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* @pb_from: pointer to source print buffer structure
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*
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* Current contents of destination print buffer (if any) are discarded.
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* Source print buffer becomes empty if a successful move occurs.
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*/
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static void tipc_printbuf_move(struct print_buf *pb_to,
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struct print_buf *pb_from)
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{
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int len;
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/* Handle the cases where contents can't be moved */
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if (!pb_to->buf)
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return;
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if (!pb_from->buf) {
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tipc_printbuf_reset(pb_to);
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return;
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}
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if (pb_to->size < pb_from->size) {
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strcpy(pb_to->buf, "*** PRINT BUFFER MOVE ERROR ***");
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pb_to->buf[pb_to->size - 1] = ~0;
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pb_to->crs = strchr(pb_to->buf, 0);
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return;
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}
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/* Copy data from char after cursor to end (if used) */
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len = pb_from->buf + pb_from->size - pb_from->crs - 2;
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if ((pb_from->buf[pb_from->size - 1] == 0) && (len > 0)) {
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strcpy(pb_to->buf, pb_from->crs + 1);
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pb_to->crs = pb_to->buf + len;
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} else
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pb_to->crs = pb_to->buf;
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/* Copy data from start to cursor (always) */
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len = pb_from->crs - pb_from->buf;
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strcpy(pb_to->crs, pb_from->buf);
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pb_to->crs += len;
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tipc_printbuf_reset(pb_from);
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}
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/**
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* tipc_printf - append formatted output to print buffer
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* @pb: pointer to print buffer
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* @fmt: formatted info to be printed
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*/
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void tipc_printf(struct print_buf *pb, const char *fmt, ...)
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{
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int i;
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va_list args;
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char *buf;
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int len;
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buf = pb->crs;
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len = pb->buf + pb->size - pb->crs;
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va_start(args, fmt);
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i = vscnprintf(buf, len, fmt, args);
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va_end(args);
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pb->crs += i;
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}
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/**
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* tipc_log_resize - change the size of the TIPC log buffer
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* @log_size: print buffer size to use
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*/
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int tipc_log_resize(int log_size)
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{
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int res = 0;
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spin_lock_bh(&print_lock);
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kfree(TIPC_LOG->buf);
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TIPC_LOG->buf = NULL;
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if (log_size) {
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if (log_size < TIPC_PB_MIN_SIZE)
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log_size = TIPC_PB_MIN_SIZE;
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res = TIPC_LOG->echo;
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tipc_printbuf_init(TIPC_LOG, kmalloc(log_size, GFP_ATOMIC),
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log_size);
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TIPC_LOG->echo = res;
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res = !TIPC_LOG->buf;
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}
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spin_unlock_bh(&print_lock);
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return res;
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}
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/**
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* tipc_log_resize_cmd - reconfigure size of TIPC log buffer
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*/
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struct sk_buff *tipc_log_resize_cmd(const void *req_tlv_area, int req_tlv_space)
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{
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u32 value;
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if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_UNSIGNED))
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return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
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value = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
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if (value > 32768)
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return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
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" (log size must be 0-32768)");
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if (tipc_log_resize(value))
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return tipc_cfg_reply_error_string(
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"unable to create specified log (log size is now 0)");
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return tipc_cfg_reply_none();
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}
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/**
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* tipc_log_dump - capture TIPC log buffer contents in configuration message
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*/
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struct sk_buff *tipc_log_dump(void)
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{
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struct sk_buff *reply;
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spin_lock_bh(&print_lock);
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if (!TIPC_LOG->buf) {
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spin_unlock_bh(&print_lock);
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reply = tipc_cfg_reply_ultra_string("log not activated\n");
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} else if (tipc_printbuf_empty(TIPC_LOG)) {
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spin_unlock_bh(&print_lock);
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reply = tipc_cfg_reply_ultra_string("log is empty\n");
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} else {
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struct tlv_desc *rep_tlv;
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struct print_buf pb;
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int str_len;
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str_len = min(TIPC_LOG->size, 32768u);
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spin_unlock_bh(&print_lock);
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reply = tipc_cfg_reply_alloc(TLV_SPACE(str_len));
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if (reply) {
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rep_tlv = (struct tlv_desc *)reply->data;
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tipc_printbuf_init(&pb, TLV_DATA(rep_tlv), str_len);
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spin_lock_bh(&print_lock);
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tipc_printbuf_move(&pb, TIPC_LOG);
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spin_unlock_bh(&print_lock);
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str_len = strlen(TLV_DATA(rep_tlv)) + 1;
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skb_put(reply, TLV_SPACE(str_len));
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TLV_SET(rep_tlv, TIPC_TLV_ULTRA_STRING, NULL, str_len);
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}
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}
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return reply;
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}
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