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Mon, 28 Sep 2026 11:01:12 -0700 (PDT) From: Gustavo Luiz Duarte Date: Mon, 28 Sep 2026 19:00:05 +0100 Subject: [PATCH net-next 3/4] netconsole: avoid printing partially updated target attributes Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260928-netcons-fixes-v1-3-bb5ffe5e698a@gmail.com> References: <20260928-netcons-fixes-v1-0-bb5ffe5e698a@gmail.com> In-Reply-To: <20260928-netcons-fixes-v1-0-bb5ffe5e698a@gmail.com> To: Breno Leitao , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Matt Mackall , =?utf-8?q?Bruno_Pr=C3=A9mont?= , Stephen Hemminger Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Gustavo Luiz Duarte , Sashiko X-Mailer: b4 0.15.2 The configfs store callbacks all serialize on dynamic_netconsole_mutex but not on the read side, so reading an attribute while it is being written returns a partially updated value. Hold dynamic_netconsole_mutex on *_show() callbacks to avoid racing with writers. Reported-by: Sashiko Closes: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260814-netcons_ipv6-v3-7-bc0915e8c75f@gmail.com Signed-off-by: Gustavo Luiz Duarte --- drivers/net/netconsole.c | 57 ++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 46 insertions(+), 11 deletions(-) diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c index 5f4311726d11..627475f16383 100644 --- a/drivers/net/netconsole.c +++ b/drivers/net/netconsole.c @@ -861,7 +861,14 @@ static ssize_t release_show(struct config_item *item, char *buf) static ssize_t dev_name_show(struct config_item *item, char *buf) { - return sysfs_emit(buf, "%s\n", to_target(item)->np.dev_name); + struct netconsole_target *nt = to_target(item); + int ret; + + dynamic_netconsole_mutex_lock(); + ret = sysfs_emit(buf, "%s\n", nt->np.dev_name); + dynamic_netconsole_mutex_unlock(); + + return ret; } static ssize_t local_port_show(struct config_item *item, char *buf) @@ -877,25 +884,39 @@ static ssize_t remote_port_show(struct config_item *item, char *buf) static ssize_t local_ip_show(struct config_item *item, char *buf) { struct netconsole_target *nt = to_target(item); + int ret; + + dynamic_netconsole_mutex_lock(); if (nt->local_ip.family == AF_UNSPEC) - return sysfs_emit(buf, "\n"); - if (nt->local_ip.family == AF_INET6) - return sysfs_emit(buf, "%pI6c\n", &nt->local_ip.in6); + ret = sysfs_emit(buf, "\n"); + else if (nt->local_ip.family == AF_INET6) + ret = sysfs_emit(buf, "%pI6c\n", &nt->local_ip.in6); else - return sysfs_emit(buf, "%pI4\n", &nt->local_ip.ip); + ret = sysfs_emit(buf, "%pI4\n", &nt->local_ip.ip); + + dynamic_netconsole_mutex_unlock(); + + return ret; } static ssize_t remote_ip_show(struct config_item *item, char *buf) { struct netconsole_target *nt = to_target(item); + int ret; + + dynamic_netconsole_mutex_lock(); if (nt->remote_ip.family == AF_UNSPEC) - return sysfs_emit(buf, "\n"); - if (nt->remote_ip.family == AF_INET6) - return sysfs_emit(buf, "%pI6c\n", &nt->remote_ip.in6); + ret = sysfs_emit(buf, "\n"); + else if (nt->remote_ip.family == AF_INET6) + ret = sysfs_emit(buf, "%pI6c\n", &nt->remote_ip.in6); else - return sysfs_emit(buf, "%pI4\n", &nt->remote_ip.ip); + ret = sysfs_emit(buf, "%pI4\n", &nt->remote_ip.ip); + + dynamic_netconsole_mutex_unlock(); + + return ret; } static ssize_t local_mac_show(struct config_item *item, char *buf) @@ -915,7 +936,14 @@ static ssize_t local_mac_show(struct config_item *item, char *buf) static ssize_t remote_mac_show(struct config_item *item, char *buf) { - return sysfs_emit(buf, "%pM\n", to_target(item)->remote_mac); + struct netconsole_target *nt = to_target(item); + int ret; + + dynamic_netconsole_mutex_lock(); + ret = sysfs_emit(buf, "%pM\n", nt->remote_mac); + dynamic_netconsole_mutex_unlock(); + + return ret; } static ssize_t transmit_errors_show(struct config_item *item, char *buf) @@ -1350,7 +1378,14 @@ static struct netconsole_target *userdata_to_target(struct userdata *ud) static ssize_t userdatum_value_show(struct config_item *item, char *buf) { - return sysfs_emit(buf, "%s\n", &(to_userdatum(item)->value[0])); + struct userdatum *udm = to_userdatum(item); + int ret; + + dynamic_netconsole_mutex_lock(); + ret = sysfs_emit(buf, "%s\n", udm->value); + dynamic_netconsole_mutex_unlock(); + + return ret; } /* Navigate configfs and calculate the lentgh of the formatted string -- 2.55.0