diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/CodingStyle | 126 | ||||
| -rw-r--r-- | Documentation/SubmitChecklist | 6 | ||||
| -rw-r--r-- | Documentation/accounting/getdelays.c | 64 | ||||
| -rw-r--r-- | Documentation/ioctl/ioctl-decoding.txt | 24 | ||||
| -rw-r--r-- | Documentation/spi/pxa2xx | 16 |
5 files changed, 205 insertions, 31 deletions
diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle index 29c1896..0ad6dcb 100644 --- a/Documentation/CodingStyle +++ b/Documentation/CodingStyle @@ -35,12 +35,37 @@ In short, 8-char indents make things easier to read, and have the added benefit of warning you when you're nesting your functions too deep. Heed that warning. +The preferred way to ease multiple indentation levels in a switch statement is +to align the "switch" and its subordinate "case" labels in the same column +instead of "double-indenting" the "case" labels. E.g.: + + switch (suffix) { + case 'G': + case 'g': + mem <<= 30; + break; + case 'M': + case 'm': + mem <<= 20; + break; + case 'K': + case 'k': + mem <<= 10; + /* fall through */ + default: + break; + } + + Don't put multiple statements on a single line unless you have something to hide: if (condition) do_this; do_something_everytime; +Don't put multiple assignments on a single line either. Kernel coding style +is super simple. Avoid tricky expressions. + Outside of comments, documentation and except in Kconfig, spaces are never used for indentation, and the above example is deliberately broken. @@ -69,7 +94,7 @@ void fun(int a, int b, int c) next_statement; } - Chapter 3: Placing Braces + Chapter 3: Placing Braces and Spaces The other issue that always comes up in C styling is the placement of braces. Unlike the indent size, there are few technical reasons to @@ -81,6 +106,20 @@ brace last on the line, and put the closing brace first, thusly: we do y } +This applies to all non-function statement blocks (if, switch, for, +while, do). E.g.: + + switch (action) { + case KOBJ_ADD: + return "add"; + case KOBJ_REMOVE: + return "remove"; + case KOBJ_CHANGE: + return "change"; + default: + return NULL; + } + However, there is one special case, namely functions: they have the opening brace at the beginning of the next line, thus: @@ -121,6 +160,49 @@ supply of new-lines on your screen is not a renewable resource (think 25-line terminal screens here), you have more empty lines to put comments on. + 3.1: Spaces + +Linux kernel style for use of spaces depends (mostly) on +function-versus-keyword usage. Use a space after (most) keywords. The +notable exceptions are sizeof, typeof, alignof, and __attribute__, which look +somewhat like functions (and are usually used with parentheses in Linux, +although they are not required in the language, as in: "sizeof info" after +"struct fileinfo info;" is declared). + +So use a space after these keywords: + if, switch, case, for, do, while +but not with sizeof, typeof, alignof, or __attribute__. E.g., + s = sizeof(struct file); + +Do not add spaces around (inside) parenthesized expressions. This example is +*bad*: + + s = sizeof( struct file ); + +When declaring pointer data or a function that returns a pointer type, the +preferred use of '*' is adjacent to the data name or function name and not +adjacent to the type name. Examples: + + char *linux_banner; + unsigned long long memparse(char *ptr, char **retptr); + char *match_strdup(substring_t *s); + +Use one space around (on each side of) most binary and ternary operators, +such as any of these: + + = + - < > * / % | & ^ <= >= == != ? : + +but no space after unary operators: + & * + - ~ ! sizeof typeof alignof __attribute__ defined + +no space before the postfix increment & decrement unary operators: + ++ -- + +no space after the prefix increment & decrement unary operators: + ++ -- + +and no space around the '.' and "->" structure member operators. + Chapter 4: Naming @@ -152,7 +234,7 @@ variable that is used to hold a temporary value. If you are afraid to mix up your local variable names, you have another problem, which is called the function-growth-hormone-imbalance syndrome. -See next chapter. +See chapter 6 (Functions). Chapter 5: Typedefs @@ -258,6 +340,20 @@ generally easily keep track of about 7 different things, anything more and it gets confused. You know you're brilliant, but maybe you'd like to understand what you did 2 weeks from now. +In source files, separate functions with one blank line. If the function is +exported, the EXPORT* macro for it should follow immediately after the closing +function brace line. E.g.: + +int system_is_up(void) +{ + return system_state == SYSTEM_RUNNING; +} +EXPORT_SYMBOL(system_is_up); + +In function prototypes, include parameter names with their data types. +Although this is not required by the C language, it is preferred in Linux +because it is a simple way to add valuable information for the reader. + Chapter 7: Centralized exiting of functions @@ -306,16 +402,36 @@ time to explain badly written code. Generally, you want your comments to tell WHAT your code does, not HOW. Also, try to avoid putting comments inside a function body: if the function is so complex that you need to separately comment parts of it, -you should probably go back to chapter 5 for a while. You can make +you should probably go back to chapter 6 for a while. You can make small comments to note or warn about something particularly clever (or ugly), but try to avoid excess. Instead, put the comments at the head of the function, telling people what it does, and possibly WHY it does it. -When commenting the kernel API functions, please use the kerneldoc format. +When commenting the kernel API functions, please use the kernel-doc format. See the files Documentation/kernel-doc-nano-HOWTO.txt and scripts/kernel-doc for details. +Linux style for comments is the C89 "/* ... */" style. +Don't use C99-style "// ..." comments. + +The preferred style for long (multi-line) comments is: + + /* + * This is the preferred style for multi-line + * comments in the Linux kernel source code. + * Please use it consistently. + * + * Description: A column of asterisks on the left side, + * with beginning and ending almost-blank lines. + */ + +It's also important to comment data, whether they are basic types or derived +types. To this end, use just one data declaration per line (no commas for +multiple data declarations). This leaves you room for a small comment on each +item, explaining its use. + + Chapter 9: You've made a mess of it That's OK, we all do. You've probably been told by your long-time Unix @@ -591,4 +707,4 @@ Kernel CodingStyle, by greg@kroah.com at OLS 2002: http://www.kroah.com/linux/talks/ols_2002_kernel_codingstyle_talk/html/ -- -Last updated on 30 April 2006. +Last updated on 2006-December-06. diff --git a/Documentation/SubmitChecklist b/Documentation/SubmitChecklist index 7ac61f6..2270efa 100644 --- a/Documentation/SubmitChecklist +++ b/Documentation/SubmitChecklist @@ -66,3 +66,9 @@ kernel patches. See Documentation/ABI/README for more information. 20: Check that it all passes `make headers_check'. + +21: Has been checked with injection of at least slab and page-allocation + fauilures. See Documentation/fault-injection/. + + If the new code is substantial, addition of subsystem-specific fault + injection might be appropriate. diff --git a/Documentation/accounting/getdelays.c b/Documentation/accounting/getdelays.c index bf2b0e2..e9126e7 100644 --- a/Documentation/accounting/getdelays.c +++ b/Documentation/accounting/getdelays.c @@ -7,6 +7,8 @@ * Copyright (C) Balbir Singh, IBM Corp. 2006 * Copyright (c) Jay Lan, SGI. 2006 * + * Compile with + * gcc -I/usr/src/linux/include getdelays.c -o getdelays */ #include <stdio.h> @@ -35,13 +37,20 @@ #define NLA_DATA(na) ((void *)((char*)(na) + NLA_HDRLEN)) #define NLA_PAYLOAD(len) (len - NLA_HDRLEN) -#define err(code, fmt, arg...) do { printf(fmt, ##arg); exit(code); } while (0) -int done = 0; -int rcvbufsz=0; - - char name[100]; -int dbg=0, print_delays=0; +#define err(code, fmt, arg...) \ + do { \ + fprintf(stderr, fmt, ##arg); \ + exit(code); \ + } while (0) + +int done; +int rcvbufsz; +char name[100]; +int dbg; +int print_delays; +int print_io_accounting; __u64 stime, utime; + #define PRINTF(fmt, arg...) { \ if (dbg) { \ printf(fmt, ##arg); \ @@ -78,8 +87,9 @@ static int create_nl_socket(int protocol) if (rcvbufsz) if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &rcvbufsz, sizeof(rcvbufsz)) < 0) { - printf("Unable to set socket rcv buf size to %d\n", - rcvbufsz); + fprintf(stderr, "Unable to set socket rcv buf size " + "to %d\n", + rcvbufsz); return -1; } @@ -186,6 +196,15 @@ void print_delayacct(struct taskstats *t) "count", "delay total", t->swapin_count, t->swapin_delay_total); } +void print_ioacct(struct taskstats *t) +{ + printf("%s: read=%llu, write=%llu, cancelled_write=%llu\n", + t->ac_comm, + (unsigned long long)t->read_bytes, + (unsigned long long)t->write_bytes, + (unsigned long long)t->cancelled_write_bytes); +} + int main(int argc, char *argv[]) { int c, rc, rep_len, aggr_len, len2, cmd_type; @@ -208,7 +227,7 @@ int main(int argc, char *argv[]) struct msgtemplate msg; while (1) { - c = getopt(argc, argv, "dw:r:m:t:p:v:l"); + c = getopt(argc, argv, "diw:r:m:t:p:v:l"); if (c < 0) break; @@ -217,6 +236,10 @@ int main(int argc, char *argv[]) printf("print delayacct stats ON\n"); print_delays = 1; break; + case 'i': + printf("printing IO accounting\n"); + print_io_accounting = 1; + break; case 'w': strncpy(logfile, optarg, MAX_FILENAME); printf("write to file %s\n", logfile); @@ -238,14 +261,12 @@ int main(int argc, char *argv[]) if (!tid) err(1, "Invalid tgid\n"); cmd_type = TASKSTATS_CMD_ATTR_TGID; - print_delays = 1; break; case 'p': tid = atoi(optarg); if (!tid) err(1, "Invalid pid\n"); cmd_type = TASKSTATS_CMD_ATTR_PID; - print_delays = 1; break; case 'v': printf("debug on\n"); @@ -277,7 +298,7 @@ int main(int argc, char *argv[]) mypid = getpid(); id = get_family_id(nl_sd); if (!id) { - printf("Error getting family id, errno %d", errno); + fprintf(stderr, "Error getting family id, errno %d\n", errno); goto err; } PRINTF("family id %d\n", id); @@ -288,7 +309,7 @@ int main(int argc, char *argv[]) &cpumask, strlen(cpumask) + 1); PRINTF("Sent register cpumask, retval %d\n", rc); if (rc < 0) { - printf("error sending register cpumask\n"); + fprintf(stderr, "error sending register cpumask\n"); goto err; } } @@ -298,7 +319,7 @@ int main(int argc, char *argv[]) cmd_type, &tid, sizeof(__u32)); PRINTF("Sent pid/tgid, retval %d\n", rc); if (rc < 0) { - printf("error sending tid/tgid cmd\n"); + fprintf(stderr, "error sending tid/tgid cmd\n"); goto done; } } @@ -310,13 +331,15 @@ int main(int argc, char *argv[]) PRINTF("received %d bytes\n", rep_len); if (rep_len < 0) { - printf("nonfatal reply error: errno %d\n", errno); + fprintf(stderr, "nonfatal reply error: errno %d\n", + errno); continue; } if (msg.n.nlmsg_type == NLMSG_ERROR || !NLMSG_OK((&msg.n), rep_len)) { struct nlmsgerr *err = NLMSG_DATA(&msg); - printf("fatal reply error, errno %d\n", err->error); + fprintf(stderr, "fatal reply error, errno %d\n", + err->error); goto done; } @@ -356,6 +379,8 @@ int main(int argc, char *argv[]) count++; if (print_delays) print_delayacct((struct taskstats *) NLA_DATA(na)); + if (print_io_accounting) + print_ioacct((struct taskstats *) NLA_DATA(na)); if (fd) { if (write(fd, NLA_DATA(na), na->nla_len) < 0) { err(1,"write error\n"); @@ -365,7 +390,9 @@ int main(int argc, char *argv[]) goto done; break; default: - printf("Unknown nested nla_type %d\n", na->nla_type); + fprintf(stderr, "Unknown nested" + " nla_type %d\n", + na->nla_type); break; } len2 += NLA_ALIGN(na->nla_len); @@ -374,7 +401,8 @@ int main(int argc, char *argv[]) break; default: - printf("Unknown nla_type %d\n", na->nla_type); + fprintf(stderr, "Unknown nla_type %d\n", + na->nla_type); break; } na = (struct nlattr *) (GENLMSG_DATA(&msg) + len); diff --git a/Documentation/ioctl/ioctl-decoding.txt b/Documentation/ioctl/ioctl-decoding.txt new file mode 100644 index 0000000..bfdf7f3 --- /dev/null +++ b/Documentation/ioctl/ioctl-decoding.txt @@ -0,0 +1,24 @@ +To decode a hex IOCTL code: + +Most architecures use this generic format, but check +include/ARCH/ioctl.h for specifics, e.g. powerpc +uses 3 bits to encode read/write and 13 bits for size. + + bits meaning + 31-30 00 - no parameters: uses _IO macro + 10 - read: _IOR + 01 - write: _IOW + 11 - read/write: _IOWR + + 29-16 size of arguments + + 15-8 ascii character supposedly + unique to each driver + + 7-0 function # + + + So for example 0x82187201 is a read with arg length of 0x218, +character 'r' function 1. Grepping the source reveals this is: + +#define VFAT_IOCTL_READDIR_BOTH _IOR('r', 1, struct dirent [2]) diff --git a/Documentation/spi/pxa2xx b/Documentation/spi/pxa2xx index a1e0ee2..f9717fe 100644 --- a/Documentation/spi/pxa2xx +++ b/Documentation/spi/pxa2xx @@ -102,7 +102,7 @@ struct pxa2xx_spi_chip { u8 tx_threshold; u8 rx_threshold; u8 dma_burst_size; - u32 timeout_microsecs; + u32 timeout; u8 enable_loopback; void (*cs_control)(u32 command); }; @@ -121,7 +121,7 @@ the PXA2xx "Developer Manual" sections on the DMA controller and SSP Controllers to determine the correct value. An SSP configured for byte-wide transfers would use a value of 8. -The "pxa2xx_spi_chip.timeout_microsecs" fields is used to efficiently handle +The "pxa2xx_spi_chip.timeout" fields is used to efficiently handle trailing bytes in the SSP receiver fifo. The correct value for this field is dependent on the SPI bus speed ("spi_board_info.max_speed_hz") and the specific slave device. Please note that the PXA2xx SSP 1 does not support trailing byte @@ -162,18 +162,18 @@ static void cs8405a_cs_control(u32 command) } static struct pxa2xx_spi_chip cs8415a_chip_info = { - .tx_threshold = 12, /* SSP hardward FIFO threshold */ - .rx_threshold = 4, /* SSP hardward FIFO threshold */ + .tx_threshold = 8, /* SSP hardward FIFO threshold */ + .rx_threshold = 8, /* SSP hardward FIFO threshold */ .dma_burst_size = 8, /* Byte wide transfers used so 8 byte bursts */ - .timeout_microsecs = 64, /* Wait at least 64usec to handle trailing */ + .timeout = 235, /* See Intel documentation */ .cs_control = cs8415a_cs_control, /* Use external chip select */ }; static struct pxa2xx_spi_chip cs8405a_chip_info = { - .tx_threshold = 12, /* SSP hardward FIFO threshold */ - .rx_threshold = 4, /* SSP hardward FIFO threshold */ + .tx_threshold = 8, /* SSP hardward FIFO threshold */ + .rx_threshold = 8, /* SSP hardward FIFO threshold */ .dma_burst_size = 8, /* Byte wide transfers used so 8 byte bursts */ - .timeout_microsecs = 64, /* Wait at least 64usec to handle trailing */ + .timeout = 235, /* See Intel documentation */ .cs_control = cs8405a_cs_control, /* Use external chip select */ }; |
