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AJvYcCVFfqH8nOcc/D8ABxswHBpqBpKzGmtLaA5FyHdM9aarIWYqCjf5qRxFQrDGRXAR54Y29TuKyCw=@vger.kernel.org X-Gm-Message-State: AOJu0YxeRQVEV+zE+vA7gUnLy5XOPw1F4kdCbDTjdIMG+Pwsrbkypw+1 erVH2uBlxCHN8j757ZNUlrEF9GppmV89yotEp/fm6BFFdM8gcXMKtgiThTquwH1GN5BMvmus4A= = X-Google-Smtp-Source: AGHT+IEppDEhXNEnJuuguSyXa29zHUAVxWcgUUPya9ABXzsuDn/hla1s/pdM9tUk5JYU8lrMptyQMBiB8Q== X-Received: from pfbfn20.prod.google.com ([2002:a05:6a00:2fd4:b0:739:8c87:ed18]) (user=tavip job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:db12:b0:220:c813:dfce with SMTP id d9443c01a7336-2296c839967mr40085235ad.39.1743611282821; Wed, 02 Apr 2025 09:28:02 -0700 (PDT) Date: Wed, 2 Apr 2025 09:27:48 -0700 In-Reply-To: <20250402162750.1671155-1-tavip@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250402162750.1671155-1-tavip@google.com> X-Mailer: git-send-email 2.49.0.472.ge94155a9ec-goog Message-ID: <20250402162750.1671155-2-tavip@google.com> Subject: [PATCH net v2 1/3] net_sched: sch_sfq: use a temporary work area for validating configuration From: Octavian Purdila To: jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, shuah@kernel.org, netdev@vger.kernel.org, Octavian Purdila X-Patchwork-Delegate: kuba@kernel.org Many configuration parameters have influence on others (e.g. divisor -> flows -> limit, depth -> limit) and so it is difficult to correctly do all of the validation before applying the configuration. And if a validation error is detected late it is difficult to roll back a partially applied configuration. To avoid these issues use a temporary work area to update and validate the configuration and only then apply the configuration to the internal state. Signed-off-by: Octavian Purdila --- net/sched/sch_sfq.c | 58 +++++++++++++++++++++++++++++++++++---------- 1 file changed, 46 insertions(+), 12 deletions(-) diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index 65d5b59da583..1af06cd5034a 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -631,6 +631,16 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt, struct red_parms *p = NULL; struct sk_buff *to_free = NULL; struct sk_buff *tail = NULL; + /* work area for validating changes before committing them */ + int limit; + unsigned int divisor; + unsigned int maxflows; + int perturb_period; + unsigned int quantum; + u8 headdrop; + u8 maxdepth; + u8 flags; + if (opt->nla_len < nla_attr_size(sizeof(*ctl))) return -EINVAL; @@ -656,36 +666,60 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt, NL_SET_ERR_MSG_MOD(extack, "invalid limit"); return -EINVAL; } + sch_tree_lock(sch); + + /* copy configuration to work area */ + limit = q->limit; + divisor = q->divisor; + headdrop = q->headdrop; + maxdepth = q->maxdepth; + maxflows = q->maxflows; + perturb_period = q->perturb_period; + quantum = q->quantum; + flags = q->flags; + + /* update and validate configuration */ if (ctl->quantum) - q->quantum = ctl->quantum; - WRITE_ONCE(q->perturb_period, ctl->perturb_period * HZ); + quantum = ctl->quantum; + perturb_period = ctl->perturb_period * HZ; if (ctl->flows) - q->maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS); + maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS); if (ctl->divisor) { - q->divisor = ctl->divisor; - q->maxflows = min_t(u32, q->maxflows, q->divisor); + divisor = ctl->divisor; + maxflows = min_t(u32, maxflows, divisor); } if (ctl_v1) { if (ctl_v1->depth) - q->maxdepth = min_t(u32, ctl_v1->depth, SFQ_MAX_DEPTH); + maxdepth = min_t(u32, ctl_v1->depth, SFQ_MAX_DEPTH); if (p) { - swap(q->red_parms, p); - red_set_parms(q->red_parms, + red_set_parms(p, ctl_v1->qth_min, ctl_v1->qth_max, ctl_v1->Wlog, ctl_v1->Plog, ctl_v1->Scell_log, NULL, ctl_v1->max_P); } - q->flags = ctl_v1->flags; - q->headdrop = ctl_v1->headdrop; + flags = ctl_v1->flags; + headdrop = ctl_v1->headdrop; } if (ctl->limit) { - q->limit = min_t(u32, ctl->limit, q->maxdepth * q->maxflows); - q->maxflows = min_t(u32, q->maxflows, q->limit); + limit = min_t(u32, ctl->limit, maxdepth * maxflows); + maxflows = min_t(u32, maxflows, limit); } + /* commit configuration, no return from this point further */ + q->limit = limit; + q->divisor = divisor; + q->headdrop = headdrop; + q->maxdepth = maxdepth; + q->maxflows = maxflows; + WRITE_ONCE(q->perturb_period, perturb_period); + q->quantum = quantum; + q->flags = flags; + if (p) + swap(q->red_parms, p); + qlen = sch->q.qlen; while (sch->q.qlen > q->limit) { dropped += sfq_drop(sch, &to_free);