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UAPI: ndctl: Fix g++-unsupported initialisation in headers 

The following code in the linux/ndctl header file:

	static inline const char *nvdimm_bus_cmd_name(unsigned cmd)
	{
		static const char * const names[] = {
			[ND_CMD_ARS_CAP] = "ars_cap",
			[ND_CMD_ARS_START] = "ars_start",
			[ND_CMD_ARS_STATUS] = "ars_status",
			[ND_CMD_CLEAR_ERROR] = "clear_error",
			[ND_CMD_CALL] = "cmd_call",
		};

		if (cmd < ARRAY_SIZE(names) && names[cmd])
			return names[cmd];
		return "unknown";
	}

is broken in a number of ways:

 (1) ARRAY_SIZE() is not generally defined.

 (2) g++ does not support "non-trivial" array initialisers fully yet.

 (3) Every file that calls this function will acquire a copy of names[].

The same goes for nvdimm_cmd_name().

Fix all three by converting to a switch statement where each case returns a
string.  That way if cmd is a constant, the compiler can trivially reduce it
and, if not, the compiler can use a shared lookup table if it thinks that is
more efficient.

A better way would be to remove these functions and their arrays from the
header entirely.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
David Howells 2018-09-06 10:19:24 +01:00 committed by Dan Williams
parent f110176633
commit 9607871f37
1 changed files with 21 additions and 27 deletions
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48
include/uapi/linux/ndctl.h
View File

@ -128,37 +128,31 @@ enum {
static inline const char *nvdimm_bus_cmd_name(unsigned cmd)
{
static const char * const names[] = {
[ND_CMD_ARS_CAP] = "ars_cap",
[ND_CMD_ARS_START] = "ars_start",
[ND_CMD_ARS_STATUS] = "ars_status",
[ND_CMD_CLEAR_ERROR] = "clear_error",
[ND_CMD_CALL] = "cmd_call",
};
if (cmd < ARRAY_SIZE(names) && names[cmd])
return names[cmd];
return "unknown";
switch (cmd) {
case ND_CMD_ARS_CAP: return "ars_cap";
case ND_CMD_ARS_START: return "ars_start";
case ND_CMD_ARS_STATUS: return "ars_status";
case ND_CMD_CLEAR_ERROR: return "clear_error";
case ND_CMD_CALL: return "cmd_call";
default: return "unknown";
}
}
static inline const char *nvdimm_cmd_name(unsigned cmd)
{
static const char * const names[] = {
[ND_CMD_SMART] = "smart",
[ND_CMD_SMART_THRESHOLD] = "smart_thresh",
[ND_CMD_DIMM_FLAGS] = "flags",
[ND_CMD_GET_CONFIG_SIZE] = "get_size",
[ND_CMD_GET_CONFIG_DATA] = "get_data",
[ND_CMD_SET_CONFIG_DATA] = "set_data",
[ND_CMD_VENDOR_EFFECT_LOG_SIZE] = "effect_size",
[ND_CMD_VENDOR_EFFECT_LOG] = "effect_log",
[ND_CMD_VENDOR] = "vendor",
[ND_CMD_CALL] = "cmd_call",
};
if (cmd < ARRAY_SIZE(names) && names[cmd])
return names[cmd];
return "unknown";
switch (cmd) {
case ND_CMD_SMART: return "smart";
case ND_CMD_SMART_THRESHOLD: return "smart_thresh";
case ND_CMD_DIMM_FLAGS: return "flags";
case ND_CMD_GET_CONFIG_SIZE: return "get_size";
case ND_CMD_GET_CONFIG_DATA: return "get_data";
case ND_CMD_SET_CONFIG_DATA: return "set_data";
case ND_CMD_VENDOR_EFFECT_LOG_SIZE: return "effect_size";
case ND_CMD_VENDOR_EFFECT_LOG: return "effect_log";
case ND_CMD_VENDOR: return "vendor";
case ND_CMD_CALL: return "cmd_call";
default: return "unknown";
}
}
#define ND_IOCTL 'N'