From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Randy.Dunlap" Subject: Re: [PATCH] pktgen: reduce stack usage Date: Fri, 18 Feb 2005 14:37:51 -0800 Message-ID: <42166E3F.2050304@osdl.org> References: <20050218134219.3f079110.rddunlap@osdl.org> <20050218221121.GA22845@electric-eye.fr.zoreil.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------060305080105070604010102" Cc: robert.olsson@its.uu.se, netdev To: Francois Romieu In-Reply-To: <20050218221121.GA22845@electric-eye.fr.zoreil.com> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org This is a multi-part message in MIME format. --------------060305080105070604010102 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Francois Romieu wrote: > Randy.Dunlap : > >>(resend) >>Any comments this time? > > > Did I miss a simultaneous use of both buffers or could it be possible to > save an extra IP_NAME_SZ bytes of data with an evil ugly union ? I don't see any simultaneous uses of the 2 buffers, so here's the union version of the patch (attached this time), although it only saves 4 bytes... so maybe the compiler had already realized that usage. Either one accomplishes a large stack reduction, but the first one is slightly more readable & maintainable (to me), and less error-prone (or more future-proof) (again, to me). Thanks, -- ~Randy --------------060305080105070604010102 Content-Type: text/x-patch; name="pktgen_stack_v2.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="pktgen_stack_v2.patch" pktgen: proc_if_write: reduce stack usage (on i386) from 776 to 292 bytes by combining/reusing locals. Signed-off-by: Randy Dunlap diffstat:= net/core/pktgen.c | 96 ++++++++++++++++++++++++------------------------------ 1 files changed, 44 insertions(+), 52 deletions(-) diff -Naurp ./net/core/pktgen.c~pktgen_stack ./net/core/pktgen.c --- ./net/core/pktgen.c~pktgen_stack 2005-02-18 13:39:12.309983016 -0800 +++ ./net/core/pktgen.c 2005-02-18 14:28:54.007696064 -0800 @@ -811,6 +811,10 @@ static int proc_if_write(struct file *fi struct pktgen_dev *pkt_dev = (struct pktgen_dev*)(data); char* pg_result = NULL; int tmp = 0; + union bufs { + char buf4[IP_NAME_SZ]; + char buf6[128]; + } bu; pg_result = &(pkt_dev->result[0]); @@ -1071,16 +1075,15 @@ static int proc_if_write(struct file *fi return count; } if (!strcmp(name, "dst_min") || !strcmp(name, "dst")) { - char buf[IP_NAME_SZ]; len = strn_len(&user_buffer[i], sizeof(pkt_dev->dst_min) - 1); if (len < 0) { return len; } - if (copy_from_user(buf, &user_buffer[i], len)) + if (copy_from_user(bu.buf4, &user_buffer[i], len)) return -EFAULT; - buf[len] = 0; - if (strcmp(buf, pkt_dev->dst_min) != 0) { + bu.buf4[len] = 0; + if (strcmp(bu.buf4, pkt_dev->dst_min) != 0) { memset(pkt_dev->dst_min, 0, sizeof(pkt_dev->dst_min)); - strncpy(pkt_dev->dst_min, buf, len); + strncpy(pkt_dev->dst_min, bu.buf4, len); pkt_dev->daddr_min = in_aton(pkt_dev->dst_min); pkt_dev->cur_daddr = pkt_dev->daddr_min; } @@ -1091,17 +1094,16 @@ static int proc_if_write(struct file *fi return count; } if (!strcmp(name, "dst_max")) { - char buf[IP_NAME_SZ]; len = strn_len(&user_buffer[i], sizeof(pkt_dev->dst_max) - 1); if (len < 0) { return len; } - if (copy_from_user(buf, &user_buffer[i], len)) + if (copy_from_user(bu.buf4, &user_buffer[i], len)) return -EFAULT; - buf[len] = 0; - if (strcmp(buf, pkt_dev->dst_max) != 0) { + bu.buf4[len] = 0; + if (strcmp(bu.buf4, pkt_dev->dst_max) != 0) { memset(pkt_dev->dst_max, 0, sizeof(pkt_dev->dst_max)); - strncpy(pkt_dev->dst_max, buf, len); + strncpy(pkt_dev->dst_max, bu.buf4, len); pkt_dev->daddr_max = in_aton(pkt_dev->dst_max); pkt_dev->cur_daddr = pkt_dev->daddr_max; } @@ -1112,108 +1114,99 @@ static int proc_if_write(struct file *fi return count; } if (!strcmp(name, "dst6")) { - char buf[128]; - len = strn_len(&user_buffer[i], 128 - 1); if (len < 0) return len; pkt_dev->flags |= F_IPV6; - if (copy_from_user(buf, &user_buffer[i], len)) + if (copy_from_user(bu.buf6, &user_buffer[i], len)) return -EFAULT; - buf[len] = 0; + bu.buf6[len] = 0; - scan_ip6(buf, pkt_dev->in6_daddr.s6_addr); - fmt_ip6(buf, pkt_dev->in6_daddr.s6_addr); + scan_ip6(bu.buf6, pkt_dev->in6_daddr.s6_addr); + fmt_ip6(bu.buf6, pkt_dev->in6_daddr.s6_addr); ipv6_addr_copy(&pkt_dev->cur_in6_daddr, &pkt_dev->in6_daddr); if(debug) - printk("pktgen: dst6 set to: %s\n", buf); + printk("pktgen: dst6 set to: %s\n", bu.buf6); i += len; - sprintf(pg_result, "OK: dst6=%s", buf); + sprintf(pg_result, "OK: dst6=%s", bu.buf6); return count; } if (!strcmp(name, "dst6_min")) { - char buf[128]; - len = strn_len(&user_buffer[i], 128 - 1); if (len < 0) return len; pkt_dev->flags |= F_IPV6; - if (copy_from_user(buf, &user_buffer[i], len)) + if (copy_from_user(bu.buf6, &user_buffer[i], len)) return -EFAULT; - buf[len] = 0; + bu.buf6[len] = 0; - scan_ip6(buf, pkt_dev->min_in6_daddr.s6_addr); - fmt_ip6(buf, pkt_dev->min_in6_daddr.s6_addr); + scan_ip6(bu.buf6, pkt_dev->min_in6_daddr.s6_addr); + fmt_ip6(bu.buf6, pkt_dev->min_in6_daddr.s6_addr); ipv6_addr_copy(&pkt_dev->cur_in6_daddr, &pkt_dev->min_in6_daddr); if(debug) - printk("pktgen: dst6_min set to: %s\n", buf); + printk("pktgen: dst6_min set to: %s\n", bu.buf6); i += len; - sprintf(pg_result, "OK: dst6_min=%s", buf); + sprintf(pg_result, "OK: dst6_min=%s", bu.buf6); return count; } if (!strcmp(name, "dst6_max")) { - char buf[128]; - len = strn_len(&user_buffer[i], 128 - 1); if (len < 0) return len; pkt_dev->flags |= F_IPV6; - if (copy_from_user(buf, &user_buffer[i], len)) + if (copy_from_user(bu.buf6, &user_buffer[i], len)) return -EFAULT; - buf[len] = 0; + bu.buf6[len] = 0; - scan_ip6(buf, pkt_dev->max_in6_daddr.s6_addr); - fmt_ip6(buf, pkt_dev->max_in6_daddr.s6_addr); + scan_ip6(bu.buf6, pkt_dev->max_in6_daddr.s6_addr); + fmt_ip6(bu.buf6, pkt_dev->max_in6_daddr.s6_addr); if(debug) - printk("pktgen: dst6_max set to: %s\n", buf); + printk("pktgen: dst6_max set to: %s\n", bu.buf6); i += len; - sprintf(pg_result, "OK: dst6_max=%s", buf); + sprintf(pg_result, "OK: dst6_max=%s", bu.buf6); return count; } if (!strcmp(name, "src6")) { - char buf[128]; - len = strn_len(&user_buffer[i], 128 - 1); if (len < 0) return len; pkt_dev->flags |= F_IPV6; - if (copy_from_user(buf, &user_buffer[i], len)) + if (copy_from_user(bu.buf6, &user_buffer[i], len)) return -EFAULT; - buf[len] = 0; + bu.buf6[len] = 0; - scan_ip6(buf, pkt_dev->in6_saddr.s6_addr); - fmt_ip6(buf, pkt_dev->in6_saddr.s6_addr); + scan_ip6(bu.buf6, pkt_dev->in6_saddr.s6_addr); + fmt_ip6(bu.buf6, pkt_dev->in6_saddr.s6_addr); ipv6_addr_copy(&pkt_dev->cur_in6_saddr, &pkt_dev->in6_saddr); if(debug) - printk("pktgen: src6 set to: %s\n", buf); + printk("pktgen: src6 set to: %s\n", bu.buf6); i += len; - sprintf(pg_result, "OK: src6=%s", buf); + sprintf(pg_result, "OK: src6=%s", bu.buf6); return count; } if (!strcmp(name, "src_min")) { - char buf[IP_NAME_SZ]; len = strn_len(&user_buffer[i], sizeof(pkt_dev->src_min) - 1); if (len < 0) { return len; } - if (copy_from_user(buf, &user_buffer[i], len)) + if (copy_from_user(bu.buf4, &user_buffer[i], len)) return -EFAULT; - buf[len] = 0; - if (strcmp(buf, pkt_dev->src_min) != 0) { + bu.buf4[len] = 0; + if (strcmp(bu.buf4, pkt_dev->src_min) != 0) { memset(pkt_dev->src_min, 0, sizeof(pkt_dev->src_min)); - strncpy(pkt_dev->src_min, buf, len); + strncpy(pkt_dev->src_min, bu.buf4, len); pkt_dev->saddr_min = in_aton(pkt_dev->src_min); pkt_dev->cur_saddr = pkt_dev->saddr_min; } @@ -1224,15 +1217,14 @@ static int proc_if_write(struct file *fi return count; } if (!strcmp(name, "src_max")) { - char buf[IP_NAME_SZ]; len = strn_len(&user_buffer[i], sizeof(pkt_dev->src_max) - 1); if (len < 0) { return len; } - if (copy_from_user(buf, &user_buffer[i], len)) + if (copy_from_user(bu.buf4, &user_buffer[i], len)) return -EFAULT; - buf[len] = 0; - if (strcmp(buf, pkt_dev->src_max) != 0) { + bu.buf4[len] = 0; + if (strcmp(bu.buf4, pkt_dev->src_max) != 0) { memset(pkt_dev->src_max, 0, sizeof(pkt_dev->src_max)); - strncpy(pkt_dev->src_max, buf, len); + strncpy(pkt_dev->src_max, bu.buf4, len); pkt_dev->saddr_max = in_aton(pkt_dev->src_max); pkt_dev->cur_saddr = pkt_dev->saddr_max; } --------------060305080105070604010102--