drivers/net/can/spi/mcp251x.c:1073:7: warning: variable 'intf1' is used uninitialized whenever 'if' condition is false
From: kernel test robot
Date: Thu Aug 04 2022 - 13:55:50 EST
tree: https://github.com/intel-lab-lkp/linux/commits/UPDATE-20220804-145223/Sebastian-W-rl/drivers-net-can-spi-mcp251x-c-Fix-race-condition-on-receive-interrupt/20220803-233455
head: ba4ce3d25ad57d7601a8bc5f41293923b46eb134
commit: ba4ce3d25ad57d7601a8bc5f41293923b46eb134 can: mcp251x: Fix race condition on receive interrupt
date: 11 hours ago
config: x86_64-randconfig-a016 (https://download.01.org/0day-ci/archive/20220805/202208050128.gFQ9dERP-lkp@xxxxxxxxx/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 26dd42705c2af0b8f6e5d6cdb32c9bd5ed9524eb)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/ba4ce3d25ad57d7601a8bc5f41293923b46eb134
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review UPDATE-20220804-145223/Sebastian-W-rl/drivers-net-can-spi-mcp251x-c-Fix-race-condition-on-receive-interrupt/20220803-233455
git checkout ba4ce3d25ad57d7601a8bc5f41293923b46eb134
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/net/can/spi/
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>
All warnings (new ones prefixed by >>):
>> drivers/net/can/spi/mcp251x.c:1073:7: warning: variable 'intf1' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (intf0 & CANINTF_RX0IF) {
^~~~~~~~~~~~~~~~~~~~~
drivers/net/can/spi/mcp251x.c:1092:7: note: uninitialized use occurs here
if (intf1 & CANINTF_RX1IF) {
^~~~~
drivers/net/can/spi/mcp251x.c:1073:3: note: remove the 'if' if its condition is always true
if (intf0 & CANINTF_RX0IF) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/can/spi/mcp251x.c:1066:24: note: initialize the variable 'intf1' to silence this warning
u8 intf, intf0, intf1, eflag, eflag0, eflag1;
^
= '\0'
>> drivers/net/can/spi/mcp251x.c:1082:8: warning: variable 'eflag1' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
if (intf0 & CANINTF_RX1IF) {
^~~~~~~~~~~~~~~~~~~~~
drivers/net/can/spi/mcp251x.c:1101:20: note: uninitialized use occurs here
eflag = eflag0 | eflag1;
^~~~~~
drivers/net/can/spi/mcp251x.c:1082:4: note: remove the 'if' if its condition is always false
if (intf0 & CANINTF_RX1IF) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> drivers/net/can/spi/mcp251x.c:1073:7: warning: variable 'eflag1' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (intf0 & CANINTF_RX0IF) {
^~~~~~~~~~~~~~~~~~~~~
drivers/net/can/spi/mcp251x.c:1101:20: note: uninitialized use occurs here
eflag = eflag0 | eflag1;
^~~~~~
drivers/net/can/spi/mcp251x.c:1073:3: note: remove the 'if' if its condition is always true
if (intf0 & CANINTF_RX0IF) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/can/spi/mcp251x.c:1066:47: note: initialize the variable 'eflag1' to silence this warning
u8 intf, intf0, intf1, eflag, eflag0, eflag1;
^
= '\0'
3 warnings generated.
vim +1073 drivers/net/can/spi/mcp251x.c
1056
1057 static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
1058 {
1059 struct mcp251x_priv *priv = dev_id;
1060 struct spi_device *spi = priv->spi;
1061 struct net_device *net = priv->net;
1062
1063 mutex_lock(&priv->mcp_lock);
1064 while (!priv->force_quit) {
1065 enum can_state new_state;
1066 u8 intf, intf0, intf1, eflag, eflag0, eflag1;
1067 u8 clear_intf = 0;
1068 int can_id = 0, data1 = 0;
1069
1070 mcp251x_read_2regs(spi, CANINTF, &intf0, &eflag0);
1071
1072 /* receive buffer 0 */
> 1073 if (intf0 & CANINTF_RX0IF) {
1074 mcp251x_hw_rx(spi, 0);
1075 /* Free one buffer ASAP
1076 * (The MCP2515/25625 does this automatically.)
1077 */
1078 if (mcp251x_is_2510(spi))
1079 mcp251x_write_bits(spi, CANINTF,
1080 CANINTF_RX0IF, 0x00);
1081
> 1082 if (intf0 & CANINTF_RX1IF) {
1083 /* buffer 1 is already known to be full, no need to re-read */
1084 intf1 = intf0;
1085 } else {
1086 /* intf needs to be read again to avoid a race condition */
1087 mcp251x_read_2regs(spi, CANINTF, &intf1, &eflag1);
1088 }
1089 }
1090
1091 /* receive buffer 1 */
1092 if (intf1 & CANINTF_RX1IF) {
1093 mcp251x_hw_rx(spi, 1);
1094 /* The MCP2515/25625 does this automatically. */
1095 if (mcp251x_is_2510(spi))
1096 clear_intf |= CANINTF_RX1IF;
1097 }
1098
1099 /* combine flags from both operations for error handling */
1100 intf = intf0 | intf1;
1101 eflag = eflag0 | eflag1;
1102
1103 /* mask out flags we don't care about */
1104 intf &= CANINTF_RX | CANINTF_TX | CANINTF_ERR;
1105
1106 /* any error or tx interrupt we need to clear? */
1107 if (intf & (CANINTF_ERR | CANINTF_TX))
1108 clear_intf |= intf & (CANINTF_ERR | CANINTF_TX);
1109 if (clear_intf)
1110 mcp251x_write_bits(spi, CANINTF, clear_intf, 0x00);
1111
1112 if (eflag & (EFLG_RX0OVR | EFLG_RX1OVR))
1113 mcp251x_write_bits(spi, EFLG, eflag, 0x00);
1114
1115 /* Update can state */
1116 if (eflag & EFLG_TXBO) {
1117 new_state = CAN_STATE_BUS_OFF;
1118 can_id |= CAN_ERR_BUSOFF;
1119 } else if (eflag & EFLG_TXEP) {
1120 new_state = CAN_STATE_ERROR_PASSIVE;
1121 can_id |= CAN_ERR_CRTL;
1122 data1 |= CAN_ERR_CRTL_TX_PASSIVE;
1123 } else if (eflag & EFLG_RXEP) {
1124 new_state = CAN_STATE_ERROR_PASSIVE;
1125 can_id |= CAN_ERR_CRTL;
1126 data1 |= CAN_ERR_CRTL_RX_PASSIVE;
1127 } else if (eflag & EFLG_TXWAR) {
1128 new_state = CAN_STATE_ERROR_WARNING;
1129 can_id |= CAN_ERR_CRTL;
1130 data1 |= CAN_ERR_CRTL_TX_WARNING;
1131 } else if (eflag & EFLG_RXWAR) {
1132 new_state = CAN_STATE_ERROR_WARNING;
1133 can_id |= CAN_ERR_CRTL;
1134 data1 |= CAN_ERR_CRTL_RX_WARNING;
1135 } else {
1136 new_state = CAN_STATE_ERROR_ACTIVE;
1137 }
1138
1139 /* Update can state statistics */
1140 switch (priv->can.state) {
1141 case CAN_STATE_ERROR_ACTIVE:
1142 if (new_state >= CAN_STATE_ERROR_WARNING &&
1143 new_state <= CAN_STATE_BUS_OFF)
1144 priv->can.can_stats.error_warning++;
1145 fallthrough;
1146 case CAN_STATE_ERROR_WARNING:
1147 if (new_state >= CAN_STATE_ERROR_PASSIVE &&
1148 new_state <= CAN_STATE_BUS_OFF)
1149 priv->can.can_stats.error_passive++;
1150 break;
1151 default:
1152 break;
1153 }
1154 priv->can.state = new_state;
1155
1156 if (intf & CANINTF_ERRIF) {
1157 /* Handle overflow counters */
1158 if (eflag & (EFLG_RX0OVR | EFLG_RX1OVR)) {
1159 if (eflag & EFLG_RX0OVR) {
1160 net->stats.rx_over_errors++;
1161 net->stats.rx_errors++;
1162 }
1163 if (eflag & EFLG_RX1OVR) {
1164 net->stats.rx_over_errors++;
1165 net->stats.rx_errors++;
1166 }
1167 can_id |= CAN_ERR_CRTL;
1168 data1 |= CAN_ERR_CRTL_RX_OVERFLOW;
1169 }
1170 mcp251x_error_skb(net, can_id, data1);
1171 }
1172
1173 if (priv->can.state == CAN_STATE_BUS_OFF) {
1174 if (priv->can.restart_ms == 0) {
1175 priv->force_quit = 1;
1176 priv->can.can_stats.bus_off++;
1177 can_bus_off(net);
1178 mcp251x_hw_sleep(spi);
1179 break;
1180 }
1181 }
1182
1183 if (intf == 0)
1184 break;
1185
1186 if (intf & CANINTF_TX) {
1187 if (priv->tx_busy) {
1188 net->stats.tx_packets++;
1189 net->stats.tx_bytes += can_get_echo_skb(net, 0,
1190 NULL);
1191 priv->tx_busy = false;
1192 }
1193 netif_wake_queue(net);
1194 }
1195 }
1196 mutex_unlock(&priv->mcp_lock);
1197 return IRQ_HANDLED;
1198 }
1199
--
0-DAY CI Kernel Test Service
https://01.org/lkp