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Re: [Qemu-devel] [PATCH v2 01/10] ipmi: remove IPMI_CHECK_CMD_LEN() macr

From: Corey Minyard
Subject: Re: [Qemu-devel] [PATCH v2 01/10] ipmi: remove IPMI_CHECK_CMD_LEN() macro
Date: Sat, 5 Mar 2016 05:41:40 -0600
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 
On 03/02/2016 04:14 AM, Cédric Le Goater wrote:

Most IPMI command handlers in the BMC simulator start with a call to
the macro IPMI_CHECK_CMD_LEN() which verifies that a minimal number of
arguments expected by the command are indeed available. To achieve
this task, the macro implicitly uses local variables which is
misleading in the code.

This patch adds a 'cmd_len_min' attribute to the struct IPMICmdHandler
defining the minimal number of arguments expected by the command and
moves this check in the global command handler ipmi_sim_handle_command().


This is much better.  One style comment inline...

Acked-by: Corey Minyard <address@hidden>


Signed-off-by: Cédric Le Goater <address@hidden>
---
  hw/ipmi/ipmi_bmc_sim.c | 137 ++++++++++++++++++++++---------------------------
  1 file changed, 62 insertions(+), 75 deletions(-)

diff --git a/hw/ipmi/ipmi_bmc_sim.c b/hw/ipmi/ipmi_bmc_sim.c
index 51d234aa1bf2..30b9fb48ea2d 100644
--- a/hw/ipmi/ipmi_bmc_sim.c
+++ b/hw/ipmi/ipmi_bmc_sim.c
@@ -155,10 +155,15 @@ typedef struct IPMISensor {
  typedef struct IPMIBmcSim IPMIBmcSim;

  #define MAX_NETFNS 64
-typedef void (*IPMICmdHandler)(IPMIBmcSim *s,
-                               uint8_t *cmd, unsigned int cmd_len,
-                               uint8_t *rsp, unsigned int *rsp_len,
-                               unsigned int max_rsp_len);
+
+typedef struct IPMICmdHandler {
+    void (*cmd_handler)(IPMIBmcSim *s,
+                        uint8_t *cmd, unsigned int cmd_len,
+                        uint8_t *rsp, unsigned int *rsp_len,
+                        unsigned int max_rsp_len);
+    unsigned int cmd_len_min;
+} IPMICmdHandler;
+
  typedef struct IPMINetfn {
      unsigned int cmd_nums;
      const IPMICmdHandler *cmd_handlers;
@@ -269,13 +274,6 @@ struct IPMIBmcSim {
          rsp[(*rsp_len)++] = (b);                           \
      } while (0)

-/* Verify that the received command is a certain length. */
-#define IPMI_CHECK_CMD_LEN(l) \
-    if (cmd_len < l) {                                     \
-        rsp[2] = IPMI_CC_REQUEST_DATA_LENGTH_INVALID;      \
-        return; \
-    }
-
  /* Check that the reservation in the command is valid. */
  #define IPMI_CHECK_RESERVATION(off, r) \
      do {                                                   \
@@ -623,14 +621,19 @@ static void ipmi_sim_handle_command(IPMIBmc *b,

      /* Odd netfns are not valid, make sure the command is registered */
      if ((netfn & 1) || !ibs->netfns[netfn / 2] ||
-                        (cmd[1] >= ibs->netfns[netfn / 2]->cmd_nums) ||
-                        (!ibs->netfns[netfn / 2]->cmd_handlers[cmd[1]])) {
+        (cmd[1] >= ibs->netfns[netfn / 2]->cmd_nums) ||
+        (!ibs->netfns[netfn / 2]->cmd_handlers[cmd[1]].cmd_handler)) {
          rsp[2] = IPMI_CC_INVALID_CMD;
          goto out;
I'm not sure of the qemu style here, but the above change makes the code hard to read. 

The qemu style really seems to be to not have big if statements like
this, so maybe this crasy check should be moved to a separate function?


      }

-    ibs->netfns[netfn / 2]->cmd_handlers[cmd[1]](ibs, cmd, cmd_len, rsp, 
rsp_len,
-                                                max_rsp_len);
+    if (cmd_len < ibs->netfns[netfn / 2]->cmd_handlers[cmd[1]].cmd_len_min) {
+        rsp[2] = IPMI_CC_REQUEST_DATA_LENGTH_INVALID;
+        goto out;
+    }
+
+    ibs->netfns[netfn / 2]->cmd_handlers[cmd[1]].cmd_handler(ibs, cmd, cmd_len,
+                                                rsp, rsp_len, max_rsp_len);

   out:
      k->handle_rsp(s, msg_id, rsp, *rsp_len);
@@ -737,7 +740,6 @@ static void chassis_control(IPMIBmcSim *ibs,
      IPMIInterface *s = ibs->parent.intf;
      IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);

-    IPMI_CHECK_CMD_LEN(3);
      switch (cmd[2] & 0xf) {
      case 0: /* power down */
          rsp[2] = k->do_hw_op(s, IPMI_POWEROFF_CHASSIS, 0);
@@ -838,7 +840,6 @@ static void set_acpi_power_state(IPMIBmcSim *ibs,
                            uint8_t *rsp, unsigned int *rsp_len,
                            unsigned int max_rsp_len)
  {
-    IPMI_CHECK_CMD_LEN(4);
      ibs->acpi_power_state[0] = cmd[2];
      ibs->acpi_power_state[1] = cmd[3];
  }
@@ -869,7 +870,6 @@ static void set_bmc_global_enables(IPMIBmcSim *ibs,
                                     uint8_t *rsp, unsigned int *rsp_len,
                                     unsigned int max_rsp_len)
  {
-    IPMI_CHECK_CMD_LEN(3);
      set_global_enables(ibs, cmd[2]);
  }

@@ -889,7 +889,6 @@ static void clr_msg_flags(IPMIBmcSim *ibs,
      IPMIInterface *s = ibs->parent.intf;
      IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);

-    IPMI_CHECK_CMD_LEN(3);
      ibs->msg_flags &= ~cmd[2];
      k->set_atn(s, attn_set(ibs), attn_irq_enabled(ibs));
  }
@@ -976,15 +975,17 @@ static void send_msg(IPMIBmcSim *ibs,
      uint8_t *buf;
      uint8_t netfn, rqLun, rsLun, rqSeq;

-    IPMI_CHECK_CMD_LEN(3);
-
      if (cmd[2] != 0) {
          /* We only handle channel 0 with no options */
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
          return;
      }

-    IPMI_CHECK_CMD_LEN(10);
+    if (cmd_len < 10) {
+        rsp[2] = IPMI_CC_REQUEST_DATA_LENGTH_INVALID;
+        return;
+    }
+
      if (cmd[3] != 0x40) {
          /* We only emulate a MC at address 0x40. */
          rsp[2] = 0x83; /* NAK on write */
@@ -1092,7 +1093,6 @@ static void set_watchdog_timer(IPMIBmcSim *ibs,
      IPMIInterfaceClass *k = IPMI_INTERFACE_GET_CLASS(s);
      unsigned int val;

-    IPMI_CHECK_CMD_LEN(8);
      val = cmd[2] & 0x7; /* Validate use */
      if (val == 0 || val > 5) {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
@@ -1217,7 +1217,6 @@ static void get_sdr(IPMIBmcSim *ibs,
      uint16_t nextrec;
      struct ipmi_sdr_header *sdrh;

-    IPMI_CHECK_CMD_LEN(8);
      if (cmd[6]) {
          IPMI_CHECK_RESERVATION(2, ibs->sdr.reservation);
      }
@@ -1271,7 +1270,6 @@ static void clear_sdr_rep(IPMIBmcSim *ibs,
                            uint8_t *rsp, unsigned int *rsp_len,
                            unsigned int max_rsp_len)
  {
-    IPMI_CHECK_CMD_LEN(8);
      IPMI_CHECK_RESERVATION(2, ibs->sdr.reservation);
      if (cmd[4] != 'C' || cmd[5] != 'L' || cmd[6] != 'R') {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
@@ -1330,7 +1328,6 @@ static void get_sel_entry(IPMIBmcSim *ibs,
  {
      unsigned int val;

-    IPMI_CHECK_CMD_LEN(8);
      if (cmd[6]) {
          IPMI_CHECK_RESERVATION(2, ibs->sel.reservation);
      }
@@ -1375,7 +1372,6 @@ static void add_sel_entry(IPMIBmcSim *ibs,
                            uint8_t *rsp, unsigned int *rsp_len,
                            unsigned int max_rsp_len)
  {
-    IPMI_CHECK_CMD_LEN(18);
      if (sel_add_event(ibs, cmd + 2)) {
          rsp[2] = IPMI_CC_OUT_OF_SPACE;
          return;
@@ -1390,7 +1386,6 @@ static void clear_sel(IPMIBmcSim *ibs,
                        uint8_t *rsp, unsigned int *rsp_len,
                        unsigned int max_rsp_len)
  {
-    IPMI_CHECK_CMD_LEN(8);
      IPMI_CHECK_RESERVATION(2, ibs->sel.reservation);
      if (cmd[4] != 'C' || cmd[5] != 'L' || cmd[6] != 'R') {
          rsp[2] = IPMI_CC_INVALID_DATA_FIELD;
@@ -1434,7 +1429,6 @@ static void set_sel_time(IPMIBmcSim *ibs,
      uint32_t val;
      struct ipmi_time now;

-    IPMI_CHECK_CMD_LEN(6);
      val = cmd[2] | (cmd[3] << 8) | (cmd[4] << 16) | (cmd[5] << 24);
      ipmi_gettime(&now);
      ibs->sel.time_offset = now.tv_sec - ((long) val);
@@ -1447,7 +1441,6 @@ static void set_sensor_evt_enable(IPMIBmcSim *ibs,
  {
      IPMISensor *sens;

-    IPMI_CHECK_CMD_LEN(4);
      if ((cmd[2] >= MAX_SENSORS) ||
              !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
@@ -1499,7 +1492,6 @@ static void get_sensor_evt_enable(IPMIBmcSim *ibs,
  {
      IPMISensor *sens;

-    IPMI_CHECK_CMD_LEN(3);
      if ((cmd[2] >= MAX_SENSORS) ||
          !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
@@ -1520,7 +1512,6 @@ static void rearm_sensor_evts(IPMIBmcSim *ibs,
  {
      IPMISensor *sens;

-    IPMI_CHECK_CMD_LEN(4);
      if ((cmd[2] >= MAX_SENSORS) ||
          !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
@@ -1542,7 +1533,6 @@ static void get_sensor_evt_status(IPMIBmcSim *ibs,
  {
      IPMISensor *sens;

-    IPMI_CHECK_CMD_LEN(3);
      if ((cmd[2] >= MAX_SENSORS) ||
          !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
@@ -1564,7 +1554,6 @@ static void get_sensor_reading(IPMIBmcSim *ibs,
  {
      IPMISensor *sens;

-    IPMI_CHECK_CMD_LEN(3);
      if ((cmd[2] >= MAX_SENSORS) ||
              !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
@@ -1587,7 +1576,6 @@ static void set_sensor_type(IPMIBmcSim *ibs,
      IPMISensor *sens;


-    IPMI_CHECK_CMD_LEN(5);
      if ((cmd[2] >= MAX_SENSORS) ||
              !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
@@ -1606,7 +1594,6 @@ static void get_sensor_type(IPMIBmcSim *ibs,
      IPMISensor *sens;


-    IPMI_CHECK_CMD_LEN(3);
      if ((cmd[2] >= MAX_SENSORS) ||
              !IPMI_SENSOR_GET_PRESENT(ibs->sensors + cmd[2])) {
          rsp[2] = IPMI_CC_REQ_ENTRY_NOT_PRESENT;
@@ -1619,10 +1606,10 @@ static void get_sensor_type(IPMIBmcSim *ibs,


  static const IPMICmdHandler chassis_cmds[] = {
-    [IPMI_CMD_GET_CHASSIS_CAPABILITIES] = chassis_capabilities,
-    [IPMI_CMD_GET_CHASSIS_STATUS] = chassis_status,
-    [IPMI_CMD_CHASSIS_CONTROL] = chassis_control,
-    [IPMI_CMD_GET_SYS_RESTART_CAUSE] = chassis_get_sys_restart_cause
+    [IPMI_CMD_GET_CHASSIS_CAPABILITIES] = { chassis_capabilities },
+    [IPMI_CMD_GET_CHASSIS_STATUS] = { chassis_status },
+    [IPMI_CMD_CHASSIS_CONTROL] = { chassis_control, 3 },
+    [IPMI_CMD_GET_SYS_RESTART_CAUSE] = { chassis_get_sys_restart_cause }
  };
  static const IPMINetfn chassis_netfn = {
      .cmd_nums = ARRAY_SIZE(chassis_cmds),
@@ -1630,13 +1617,13 @@ static const IPMINetfn chassis_netfn = {
  };

  static const IPMICmdHandler sensor_event_cmds[] = {
-    [IPMI_CMD_SET_SENSOR_EVT_ENABLE] = set_sensor_evt_enable,
-    [IPMI_CMD_GET_SENSOR_EVT_ENABLE] = get_sensor_evt_enable,
-    [IPMI_CMD_REARM_SENSOR_EVTS] = rearm_sensor_evts,
-    [IPMI_CMD_GET_SENSOR_EVT_STATUS] = get_sensor_evt_status,
-    [IPMI_CMD_GET_SENSOR_READING] = get_sensor_reading,
-    [IPMI_CMD_SET_SENSOR_TYPE] = set_sensor_type,
-    [IPMI_CMD_GET_SENSOR_TYPE] = get_sensor_type,
+    [IPMI_CMD_SET_SENSOR_EVT_ENABLE] = { set_sensor_evt_enable, 4 },
+    [IPMI_CMD_GET_SENSOR_EVT_ENABLE] = { get_sensor_evt_enable, 3 },
+    [IPMI_CMD_REARM_SENSOR_EVTS] = { rearm_sensor_evts, 4 },
+    [IPMI_CMD_GET_SENSOR_EVT_STATUS] = { get_sensor_evt_status, 3 },
+    [IPMI_CMD_GET_SENSOR_READING] = { get_sensor_reading, 3 },
+    [IPMI_CMD_SET_SENSOR_TYPE] = { set_sensor_type, 5 },
+    [IPMI_CMD_GET_SENSOR_TYPE] = { get_sensor_type, 3 },
  };
  static const IPMINetfn sensor_event_netfn = {
      .cmd_nums = ARRAY_SIZE(sensor_event_cmds),
@@ -1644,22 +1631,22 @@ static const IPMINetfn sensor_event_netfn = {
  };

  static const IPMICmdHandler app_cmds[] = {
-    [IPMI_CMD_GET_DEVICE_ID] = get_device_id,
-    [IPMI_CMD_COLD_RESET] = cold_reset,
-    [IPMI_CMD_WARM_RESET] = warm_reset,
-    [IPMI_CMD_SET_ACPI_POWER_STATE] = set_acpi_power_state,
-    [IPMI_CMD_GET_ACPI_POWER_STATE] = get_acpi_power_state,
-    [IPMI_CMD_GET_DEVICE_GUID] = get_device_guid,
-    [IPMI_CMD_SET_BMC_GLOBAL_ENABLES] = set_bmc_global_enables,
-    [IPMI_CMD_GET_BMC_GLOBAL_ENABLES] = get_bmc_global_enables,
-    [IPMI_CMD_CLR_MSG_FLAGS] = clr_msg_flags,
-    [IPMI_CMD_GET_MSG_FLAGS] = get_msg_flags,
-    [IPMI_CMD_GET_MSG] = get_msg,
-    [IPMI_CMD_SEND_MSG] = send_msg,
-    [IPMI_CMD_READ_EVT_MSG_BUF] = read_evt_msg_buf,
-    [IPMI_CMD_RESET_WATCHDOG_TIMER] = reset_watchdog_timer,
-    [IPMI_CMD_SET_WATCHDOG_TIMER] = set_watchdog_timer,
-    [IPMI_CMD_GET_WATCHDOG_TIMER] = get_watchdog_timer,
+    [IPMI_CMD_GET_DEVICE_ID] = { get_device_id },
+    [IPMI_CMD_COLD_RESET] = { cold_reset },
+    [IPMI_CMD_WARM_RESET] = { warm_reset },
+    [IPMI_CMD_SET_ACPI_POWER_STATE] = { set_acpi_power_state, 4 },
+    [IPMI_CMD_GET_ACPI_POWER_STATE] = { get_acpi_power_state },
+    [IPMI_CMD_GET_DEVICE_GUID] = { get_device_guid },
+    [IPMI_CMD_SET_BMC_GLOBAL_ENABLES] = { set_bmc_global_enables, 3 },
+    [IPMI_CMD_GET_BMC_GLOBAL_ENABLES] = { get_bmc_global_enables },
+    [IPMI_CMD_CLR_MSG_FLAGS] = { clr_msg_flags, 3 },
+    [IPMI_CMD_GET_MSG_FLAGS] = { get_msg_flags },
+    [IPMI_CMD_GET_MSG] = { get_msg },
+    [IPMI_CMD_SEND_MSG] = { send_msg, 3 },
+    [IPMI_CMD_READ_EVT_MSG_BUF] = { read_evt_msg_buf },
+    [IPMI_CMD_RESET_WATCHDOG_TIMER] = { reset_watchdog_timer },
+    [IPMI_CMD_SET_WATCHDOG_TIMER] = { set_watchdog_timer, 8 },
+    [IPMI_CMD_GET_WATCHDOG_TIMER] = { get_watchdog_timer },
  };
  static const IPMINetfn app_netfn = {
      .cmd_nums = ARRAY_SIZE(app_cmds),
@@ -1667,18 +1654,18 @@ static const IPMINetfn app_netfn = {
  };

  static const IPMICmdHandler storage_cmds[] = {
-    [IPMI_CMD_GET_SDR_REP_INFO] = get_sdr_rep_info,
-    [IPMI_CMD_RESERVE_SDR_REP] = reserve_sdr_rep,
-    [IPMI_CMD_GET_SDR] = get_sdr,
-    [IPMI_CMD_ADD_SDR] = add_sdr,
-    [IPMI_CMD_CLEAR_SDR_REP] = clear_sdr_rep,
-    [IPMI_CMD_GET_SEL_INFO] = get_sel_info,
-    [IPMI_CMD_RESERVE_SEL] = reserve_sel,
-    [IPMI_CMD_GET_SEL_ENTRY] = get_sel_entry,
-    [IPMI_CMD_ADD_SEL_ENTRY] = add_sel_entry,
-    [IPMI_CMD_CLEAR_SEL] = clear_sel,
-    [IPMI_CMD_GET_SEL_TIME] = get_sel_time,
-    [IPMI_CMD_SET_SEL_TIME] = set_sel_time,
+    [IPMI_CMD_GET_SDR_REP_INFO] = { get_sdr_rep_info },
+    [IPMI_CMD_RESERVE_SDR_REP] = { reserve_sdr_rep },
+    [IPMI_CMD_GET_SDR] = { get_sdr, 8 },
+    [IPMI_CMD_ADD_SDR] = { add_sdr },
+    [IPMI_CMD_CLEAR_SDR_REP] = { clear_sdr_rep, 8 },
+    [IPMI_CMD_GET_SEL_INFO] = { get_sel_info },
+    [IPMI_CMD_RESERVE_SEL] = { reserve_sel },
+    [IPMI_CMD_GET_SEL_ENTRY] = { get_sel_entry, 8 },
+    [IPMI_CMD_ADD_SEL_ENTRY] = { add_sel_entry, 18 },
+    [IPMI_CMD_CLEAR_SEL] = { clear_sel, 8 },
+    [IPMI_CMD_GET_SEL_TIME] = { get_sel_time, 6 },
+    [IPMI_CMD_SET_SEL_TIME] = { set_sel_time },
  };

  static const IPMINetfn storage_netfn = {
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