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Re: [Qemu-devel] [PATCH v2 2/9] ipmi: replace goto by a return statement

From: Marcel Apfelbaum
Subject: Re: [Qemu-devel] [PATCH v2 2/9] ipmi: replace goto by a return statement
Date: Fri, 22 Jan 2016 07:49:48 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 
On 01/21/2016 07:18 PM, Cédric Le Goater wrote:

Each routine using the IPMI_ADD_RSP_DATA, IPMI_CHECK_CMD_LEN or
IPMI_CHECK_RESERVATION macros needs to define a goto label 'out' to
handle hidden errors. Using directly a return statement as the same
effect and it removes the fact that 'out' needs to be defined.

The code exits in ipmi_sim_handle_command() are a little different
from the rest and a "possible" error in the macro IPMI_ADD_RSP_DATA is
handled before making use of it. This might be a bit excessive as a
minimum response len is currently 300 bytes and the patch checks that
at least 3 are available.

Signed-off-by: Cédric Le Goater <address@hidden>
---
  hw/ipmi/ipmi_bmc_sim.c | 140 +++++++++++++++----------------------------------
  1 file changed, 41 insertions(+), 99 deletions(-)

diff --git a/hw/ipmi/ipmi_bmc_sim.c b/hw/ipmi/ipmi_bmc_sim.c
index 0a59e539f549..e42c7e86c344 100644
--- a/hw/ipmi/ipmi_bmc_sim.c
+++ b/hw/ipmi/ipmi_bmc_sim.c
@@ -258,7 +258,7 @@ struct IPMIBmcSim {
      do {                                                   \
          if (*rsp_len >= max_rsp_len) {                     \
              rsp[2] = IPMI_CC_REQUEST_DATA_TRUNCATED;       \
-            goto out;                                      \
+            return;                                        \
          }                                                  \
          rsp[(*rsp_len)++] = (b);                           \
      } while (0)
@@ -267,7 +267,7 @@ struct IPMIBmcSim {
  #define IPMI_CHECK_CMD_LEN(l) \
      if (cmd_len < l) {                                     \
          rsp[2] = IPMI_CC_REQUEST_DATA_LENGTH_INVALID;      \
-        goto out; \
+        return; \
      }

  /* Check that the reservation in the command is valid. */
@@ -275,7 +275,7 @@ struct IPMIBmcSim {
      do {                                                   \
          if ((cmd[off] | (cmd[off + 1] << 8)) != r) {       \
              rsp[2] = IPMI_CC_INVALID_RESERVATION;          \
-            goto out;                                      \
+            return;                                        \
          }                                                  \
      } while (0)

@@ -453,14 +453,12 @@ static void gen_event(IPMIBmcSim *ibs, unsigned int 
sens_num, uint8_t deassert,
      }

      if (ibs->msg_flags & IPMI_BMC_MSG_FLAG_EVT_BUF_FULL) {
-        goto out;
+        return;
      }

      memcpy(ibs->evtbuf, evt, 16);
      ibs->msg_flags |= IPMI_BMC_MSG_FLAG_EVT_BUF_FULL;
      k->set_atn(s, 1, attn_irq_enabled(ibs));
- out:
-    return;
  }

  static void sensor_set_discrete_bit(IPMIBmcSim *ibs, unsigned int sensor,
@@ -581,6 +579,11 @@ static void ipmi_sim_handle_command(IPMIBmc *b,

      /* Set up the response, set the low bit of NETFN. */
      /* Note that max_rsp_len must be at least 3 */
+    if (max_rsp_len < 3) {
+        rsp[2] = IPMI_CC_REQUEST_DATA_TRUNCATED;
+        goto out;
+    }
+
      IPMI_ADD_RSP_DATA(cmd[0] | 0x04);
      IPMI_ADD_RSP_DATA(cmd[1]);
      IPMI_ADD_RSP_DATA(0); /* Assume success */
@@ -698,8 +701,6 @@ static void chassis_capabilities(IPMIBmcSim *ibs,
      IPMI_ADD_RSP_DATA(ibs->parent.slave_addr);
      IPMI_ADD_RSP_DATA(ibs->parent.slave_addr);
      IPMI_ADD_RSP_DATA(ibs->parent.slave_addr);
- out:
-    return;
  }

  static void chassis_status(IPMIBmcSim *ibs,
@@ -711,8 +712,6 @@ static void chassis_status(IPMIBmcSim *ibs,
      IPMI_ADD_RSP_DATA(0);
      IPMI_ADD_RSP_DATA(0);
      IPMI_ADD_RSP_DATA(0);
- out:
-    return;
  }

  static void chassis_control(IPMIBmcSim *ibs,
@@ -746,10 +745,8 @@ static void chassis_control(IPMIBmcSim *ibs,
          break;
      default:
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }
- out:
-    return;
  }

  static void get_device_id(IPMIBmcSim *ibs,
@@ -768,8 +765,6 @@ static void get_device_id(IPMIBmcSim *ibs,
      IPMI_ADD_RSP_DATA(ibs->mfg_id[2]);
      IPMI_ADD_RSP_DATA(ibs->product_id[0]);
      IPMI_ADD_RSP_DATA(ibs->product_id[1]);
- out:
-    return;
  }

  static void set_global_enables(IPMIBmcSim *ibs, uint8_t val)
@@ -822,8 +817,6 @@ static void set_bmc_global_enables(IPMIBmcSim *ibs,
  {
      IPMI_CHECK_CMD_LEN(3);
      set_global_enables(ibs, cmd[2]);
- out:
-    return;
  }

  static void get_bmc_global_enables(IPMIBmcSim *ibs,
@@ -832,8 +825,6 @@ static void get_bmc_global_enables(IPMIBmcSim *ibs,
                                     unsigned int max_rsp_len)
  {
      IPMI_ADD_RSP_DATA(ibs->bmc_global_enables);
- out:
-    return;
  }

  static void clr_msg_flags(IPMIBmcSim *ibs,
@@ -847,8 +838,6 @@ static void clr_msg_flags(IPMIBmcSim *ibs,
      IPMI_CHECK_CMD_LEN(3);
      ibs->msg_flags &= ~cmd[2];
      k->set_atn(s, attn_set(ibs), attn_irq_enabled(ibs));
- out:
-    return;
  }

  static void get_msg_flags(IPMIBmcSim *ibs,
@@ -857,8 +846,6 @@ static void get_msg_flags(IPMIBmcSim *ibs,
                            unsigned int max_rsp_len)
  {
      IPMI_ADD_RSP_DATA(ibs->msg_flags);
- out:
-    return;
  }

  static void read_evt_msg_buf(IPMIBmcSim *ibs,
@@ -872,15 +859,13 @@ static void read_evt_msg_buf(IPMIBmcSim *ibs,

      if (!(ibs->msg_flags & IPMI_BMC_MSG_FLAG_EVT_BUF_FULL)) {
          rsp[2] = 0x80;
-        goto out;
+        return;
      }
      for (i = 0; i < 16; i++) {
          IPMI_ADD_RSP_DATA(ibs->evtbuf[i]);
      }
      ibs->msg_flags &= ~IPMI_BMC_MSG_FLAG_EVT_BUF_FULL;
      k->set_atn(s, attn_set(ibs), attn_irq_enabled(ibs));
- out:
-    return;
  }

  static void get_msg(IPMIBmcSim *ibs,
@@ -911,7 +896,7 @@ static void get_msg(IPMIBmcSim *ibs,
          k->set_atn(s, attn_set(ibs), attn_irq_enabled(ibs));
      }

- out:
+out:
      qemu_mutex_unlock(&ibs->lock);
      return;
  }
@@ -942,14 +927,14 @@ static void send_msg(IPMIBmcSim *ibs,
      if (cmd[2] != 0) {
          /* We only handle channel 0 with no options */
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }

      IPMI_CHECK_CMD_LEN(10);
      if (cmd[3] != 0x40) {
          /* We only emulate a MC at address 0x40. */
          rsp[2] = 0x83; /* NAK on write */
-        goto out;
+        return;
      }

      cmd += 3; /* Skip the header. */
@@ -961,7 +946,7 @@ static void send_msg(IPMIBmcSim *ibs,
       */
      if (ipmb_checksum(cmd, cmd_len, 0) != 0 ||
          cmd[3] != 0x20) { /* Improper response address */
-        goto out; /* No response */
+        return; /* No response */
      }

      netfn = cmd[1] >> 2;
@@ -971,7 +956,7 @@ static void send_msg(IPMIBmcSim *ibs,

      if (rqLun != 2) {
          /* We only support LUN 2 coming back to us. */
-        goto out;
+        return;
      }

      msg = g_malloc(sizeof(*msg));
@@ -1011,9 +996,6 @@ static void send_msg(IPMIBmcSim *ibs,
      ibs->msg_flags |= IPMI_BMC_MSG_FLAG_RCV_MSG_QUEUE;
      k->set_atn(s, 1, attn_irq_enabled(ibs));
      qemu_mutex_unlock(&ibs->lock);
-
- out:
-    return;
  }

  static void do_watchdog_reset(IPMIBmcSim *ibs)
@@ -1042,11 +1024,9 @@ static void reset_watchdog_timer(IPMIBmcSim *ibs,
  {
      if (!ibs->watchdog_initialized) {
          rsp[2] = 0x80;
-        goto out;
+        return;
      }
      do_watchdog_reset(ibs);
- out:
-    return;
  }

  static void set_watchdog_timer(IPMIBmcSim *ibs,
@@ -1062,7 +1042,7 @@ static void set_watchdog_timer(IPMIBmcSim *ibs,
      val = cmd[2] & 0x7; /* Validate use */
      if (val == 0 || val > 5) {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }
      val = cmd[3] & 0x7; /* Validate action */
      switch (val) {
@@ -1086,7 +1066,7 @@ static void set_watchdog_timer(IPMIBmcSim *ibs,
      }
      if (rsp[2]) {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }

      val = (cmd[3] >> 4) & 0x7; /* Validate preaction */
@@ -1099,12 +1079,12 @@ static void set_watchdog_timer(IPMIBmcSim *ibs,
          if (!k->do_hw_op(s, IPMI_SEND_NMI, 1)) {
              /* NMI not supported. */
              rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-            goto out;
+            return;
          }
      default:
          /* We don't support PRE_SMI */
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }

      ibs->watchdog_initialized = 1;
@@ -1118,8 +1098,6 @@ static void set_watchdog_timer(IPMIBmcSim *ibs,
      } else {
          ibs->watchdog_running = 0;
      }
- out:
-    return;
  }

  static void get_watchdog_timer(IPMIBmcSim *ibs,
@@ -1141,8 +1119,6 @@ static void get_watchdog_timer(IPMIBmcSim *ibs,
          IPMI_ADD_RSP_DATA(0);
          IPMI_ADD_RSP_DATA(0);
      }
- out:
-    return;
  }

  static void get_sdr_rep_info(IPMIBmcSim *ibs,
@@ -1165,8 +1141,6 @@ static void get_sdr_rep_info(IPMIBmcSim *ibs,
      }
      /* Only modal support, reserve supported */
      IPMI_ADD_RSP_DATA((ibs->sdr.overflow << 7) | 0x22);
- out:
-    return;
  }

  static void reserve_sdr_rep(IPMIBmcSim *ibs,
@@ -1176,8 +1150,6 @@ static void reserve_sdr_rep(IPMIBmcSim *ibs,
  {
      IPMI_ADD_RSP_DATA(ibs->sdr.reservation & 0xff);
      IPMI_ADD_RSP_DATA((ibs->sdr.reservation >> 8) & 0xff);
- out:
-    return;
  }

  static void get_sdr(IPMIBmcSim *ibs,
@@ -1196,11 +1168,11 @@ static void get_sdr(IPMIBmcSim *ibs,
      if (sdr_find_entry(&ibs->sdr, cmd[4] | (cmd[5] << 8),
                         &pos, &nextrec)) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
-        goto out;
+        return;
      }
      if (cmd[6] > (ibs->sdr.sdr[pos + 4])) {
          rsp[2] = IPMI_CC_PARM_OUT_OF_RANGE;
-        goto out;
+        return;
      }

      IPMI_ADD_RSP_DATA(nextrec & 0xff);
@@ -1212,12 +1184,10 @@ static void get_sdr(IPMIBmcSim *ibs,

      if ((cmd[7] + *rsp_len) > max_rsp_len) {
          rsp[2] = IPMI_CC_CANNOT_RETURN_REQ_NUM_BYTES;
-        goto out;
+        return;
      }
      memcpy(rsp + *rsp_len, ibs->sdr.sdr + pos + cmd[6], cmd[7]);
      *rsp_len += cmd[7];
- out:
-    return;
  }

  static void add_sdr(IPMIBmcSim *ibs,
@@ -1229,12 +1199,10 @@ static void add_sdr(IPMIBmcSim *ibs,

      if (sdr_add_entry(ibs, cmd + 2, cmd_len - 2, &recid)) {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }
      IPMI_ADD_RSP_DATA(recid & 0xff);
      IPMI_ADD_RSP_DATA((recid >> 8) & 0xff);
- out:
-    return;
  }

  static void clear_sdr_rep(IPMIBmcSim *ibs,
@@ -1246,7 +1214,7 @@ static void clear_sdr_rep(IPMIBmcSim *ibs,
      IPMI_CHECK_RESERVATION(2, ibs->sdr.reservation);
      if (cmd[4] != 'C' || cmd[5] != 'L' || cmd[6] != 'R') {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }
      if (cmd[7] == 0xaa) {
          ibs->sdr.next_free = 0;
@@ -1258,10 +1226,8 @@ static void clear_sdr_rep(IPMIBmcSim *ibs,
          IPMI_ADD_RSP_DATA(1); /* Erasure complete */
      } else {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }
- out:
-    return;
  }

  static void get_sel_info(IPMIBmcSim *ibs,
@@ -1285,8 +1251,6 @@ static void get_sel_info(IPMIBmcSim *ibs,
      }
      /* Only support Reserve SEL */
      IPMI_ADD_RSP_DATA((ibs->sel.overflow << 7) | 0x02);
- out:
-    return;
  }

  static void reserve_sel(IPMIBmcSim *ibs,
@@ -1296,8 +1260,6 @@ static void reserve_sel(IPMIBmcSim *ibs,
  {
      IPMI_ADD_RSP_DATA(ibs->sel.reservation & 0xff);
      IPMI_ADD_RSP_DATA((ibs->sel.reservation >> 8) & 0xff);
- out:
-    return;
  }

  static void get_sel_entry(IPMIBmcSim *ibs,
@@ -1313,17 +1275,17 @@ static void get_sel_entry(IPMIBmcSim *ibs,
      }
      if (ibs->sel.next_free == 0) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
-        goto out;
+        return;
      }
      if (cmd[6] > 15) {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }
      if (cmd[7] == 0xff) {
          cmd[7] = 16;
      } else if ((cmd[7] + cmd[6]) > 16) {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      } else {
          cmd[7] += cmd[6];
      }
@@ -1333,7 +1295,7 @@ static void get_sel_entry(IPMIBmcSim *ibs,
          val = ibs->sel.next_free - 1;
      } else if (val >= ibs->sel.next_free) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
-        goto out;
+        return;
      }
      if ((val + 1) == ibs->sel.next_free) {
          IPMI_ADD_RSP_DATA(0xff);
@@ -1345,8 +1307,6 @@ static void get_sel_entry(IPMIBmcSim *ibs,
      for (; cmd[6] < cmd[7]; cmd[6]++) {
          IPMI_ADD_RSP_DATA(ibs->sel.sel[val][cmd[6]]);
      }
- out:
-    return;
  }

  static void add_sel_entry(IPMIBmcSim *ibs,
@@ -1357,13 +1317,11 @@ static void add_sel_entry(IPMIBmcSim *ibs,
      IPMI_CHECK_CMD_LEN(18);
      if (sel_add_event(ibs, cmd + 2)) {
          rsp[2] = IPMI_CC_OUT_OF_SPACE;
-        goto out;
+        return;
      }
      /* sel_add_event fills in the record number. */
      IPMI_ADD_RSP_DATA(cmd[2]);
      IPMI_ADD_RSP_DATA(cmd[3]);
- out:
-    return;
  }

  static void clear_sel(IPMIBmcSim *ibs,
@@ -1375,7 +1333,7 @@ static void clear_sel(IPMIBmcSim *ibs,
      IPMI_CHECK_RESERVATION(2, ibs->sel.reservation);
      if (cmd[4] != 'C' || cmd[5] != 'L' || cmd[6] != 'R') {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }
      if (cmd[7] == 0xaa) {
          ibs->sel.next_free = 0;
@@ -1387,10 +1345,8 @@ static void clear_sel(IPMIBmcSim *ibs,
          IPMI_ADD_RSP_DATA(1); /* Erasure complete */
      } else {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }
- out:
-    return;
  }

  static void get_sel_time(IPMIBmcSim *ibs,
@@ -1407,8 +1363,6 @@ static void get_sel_time(IPMIBmcSim *ibs,
      IPMI_ADD_RSP_DATA((val >> 8) & 0xff);
      IPMI_ADD_RSP_DATA((val >> 16) & 0xff);
      IPMI_ADD_RSP_DATA((val >> 24) & 0xff);
- out:
-    return;
  }

  static void set_sel_time(IPMIBmcSim *ibs,
@@ -1423,8 +1377,6 @@ static void set_sel_time(IPMIBmcSim *ibs,
      val = cmd[2] | (cmd[3] << 8) | (cmd[4] << 16) | (cmd[5] << 24);
      ipmi_gettime(&now);
      ibs->sel.time_offset = now.tv_sec - ((long) val);
- out:
-    return;
  }

  static void set_sensor_evt_enable(IPMIBmcSim *ibs,
@@ -1438,7 +1390,7 @@ static void set_sensor_evt_enable(IPMIBmcSim *ibs,
      if ((cmd[2] > MAX_SENSORS) ||
              !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
-        goto out;
+        return;
      }
      sens = ibs->sensors + cmd[2];
      switch ((cmd[3] >> 4) & 0x3) {
@@ -1474,11 +1426,9 @@ static void set_sensor_evt_enable(IPMIBmcSim *ibs,
          break;
      case 3:
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
-        goto out;
+        return;
      }
      IPMI_SENSOR_SET_RET_STATUS(sens, cmd[3]);
- out:
-    return;
  }

  static void get_sensor_evt_enable(IPMIBmcSim *ibs,
@@ -1492,7 +1442,7 @@ static void get_sensor_evt_enable(IPMIBmcSim *ibs,
      if ((cmd[2] > MAX_SENSORS) ||
          !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
-        goto out;
+        return;
      }
      sens = ibs->sensors + cmd[2];
      IPMI_ADD_RSP_DATA(IPMI_SENSOR_GET_RET_STATUS(sens));
@@ -1500,8 +1450,6 @@ static void get_sensor_evt_enable(IPMIBmcSim *ibs,
      IPMI_ADD_RSP_DATA((sens->assert_enable >> 8) & 0xff);
      IPMI_ADD_RSP_DATA(sens->deassert_enable & 0xff);
      IPMI_ADD_RSP_DATA((sens->deassert_enable >> 8) & 0xff);
- out:
-    return;
  }

  static void rearm_sensor_evts(IPMIBmcSim *ibs,
@@ -1515,17 +1463,15 @@ static void rearm_sensor_evts(IPMIBmcSim *ibs,
      if ((cmd[2] > MAX_SENSORS) ||
          !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
-        goto out;
+        return;
      }
      sens = ibs->sensors + cmd[2];

      if ((cmd[3] & 0x80) == 0) {
          /* Just clear everything */
          sens->states = 0;
-        goto out;
+        return;
      }
- out:
-    return;
  }

  static void get_sensor_evt_status(IPMIBmcSim *ibs,
@@ -1539,7 +1485,7 @@ static void get_sensor_evt_status(IPMIBmcSim *ibs,
      if ((cmd[2] > MAX_SENSORS) ||
          !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
-        goto out;
+        return;
      }
      sens = ibs->sensors + cmd[2];
      IPMI_ADD_RSP_DATA(sens->reading);
@@ -1548,8 +1494,6 @@ static void get_sensor_evt_status(IPMIBmcSim *ibs,
      IPMI_ADD_RSP_DATA((sens->assert_states >> 8) & 0xff);
      IPMI_ADD_RSP_DATA(sens->deassert_states & 0xff);
      IPMI_ADD_RSP_DATA((sens->deassert_states >> 8) & 0xff);
- out:
-    return;
  }

  static void get_sensor_reading(IPMIBmcSim *ibs,
@@ -1563,7 +1507,7 @@ static void get_sensor_reading(IPMIBmcSim *ibs,
      if ((cmd[2] > MAX_SENSORS) ||
              !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
-        goto out;
+        return;
      }
      sens = ibs->sensors + cmd[2];
      IPMI_ADD_RSP_DATA(sens->reading);
@@ -1572,8 +1516,6 @@ static void get_sensor_reading(IPMIBmcSim *ibs,
      if (IPMI_SENSOR_IS_DISCRETE(sens)) {
          IPMI_ADD_RSP_DATA((sens->states >> 8) & 0xff);
      }
- out:
-    return;
  }

  static const IPMICmdHandler chassis_cmds[IPMI_NETFN_CHASSIS_MAXCMD] = {



Reviewed-by: Marcel Apfelbaum <address@hidden>

Thanks for taking care of this,
Marcel
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