Linux kernel & device driver programming

Cross-Referenced Linux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]
  1 #ifndef _LINUX_MSG_H
  2 #define _LINUX_MSG_H
  3 
  4 #include <linux/ipc.h>
  5 
  6 /* ipcs ctl commands */
  7 #define MSG_STAT 11
  8 #define MSG_INFO 12
  9 
 10 /* msgrcv options */
 11 #define MSG_NOERROR     010000  /* no error if message is too big */
 12 #define MSG_EXCEPT      020000  /* recv any msg except of specified type.*/
 13 
 14 /* Obsolete, used only for backwards compatibility and libc5 compiles */
 15 struct msqid_ds {
 16         struct ipc_perm msg_perm;
 17         struct msg *msg_first;          /* first message on queue,unused  */
 18         struct msg *msg_last;           /* last message in queue,unused */
 19         __kernel_time_t msg_stime;      /* last msgsnd time */
 20         __kernel_time_t msg_rtime;      /* last msgrcv time */
 21         __kernel_time_t msg_ctime;      /* last change time */
 22         unsigned long  msg_lcbytes;     /* Reuse junk fields for 32 bit */
 23         unsigned long  msg_lqbytes;     /* ditto */
 24         unsigned short msg_cbytes;      /* current number of bytes on queue */
 25         unsigned short msg_qnum;        /* number of messages in queue */
 26         unsigned short msg_qbytes;      /* max number of bytes on queue */
 27         __kernel_ipc_pid_t msg_lspid;   /* pid of last msgsnd */
 28         __kernel_ipc_pid_t msg_lrpid;   /* last receive pid */
 29 };
 30 
 31 /* Include the definition of msqid64_ds */
 32 #include <asm/msgbuf.h>
 33 
 34 /* message buffer for msgsnd and msgrcv calls */
 35 struct msgbuf {
 36         long mtype;         /* type of message */
 37         char mtext[1];      /* message text */
 38 };
 39 
 40 /* buffer for msgctl calls IPC_INFO, MSG_INFO */
 41 struct msginfo {
 42         int msgpool;
 43         int msgmap; 
 44         int msgmax; 
 45         int msgmnb; 
 46         int msgmni; 
 47         int msgssz; 
 48         int msgtql; 
 49         unsigned short  msgseg; 
 50 };
 51 
 52 /*
 53  * Scaling factor to compute msgmni:
 54  * the memory dedicated to msg queues (msgmni * msgmnb) should occupy
 55  * at most 1/MSG_MEM_SCALE of the lowmem (see the formula in ipc/msg.c):
 56  * up to 8MB       : msgmni = 16 (MSGMNI)
 57  * 4 GB            : msgmni = 8K
 58  * more than 16 GB : msgmni = 32K (IPCMNI)
 59  */
 60 #define MSG_MEM_SCALE 32
 61 
 62 #define MSGMNI    16   /* <= IPCMNI */     /* max # of msg queue identifiers */
 63 #define MSGMAX  8192   /* <= INT_MAX */   /* max size of message (bytes) */
 64 #define MSGMNB 16384   /* <= INT_MAX */   /* default max size of a message queue */
 65 
 66 /* unused */
 67 #define MSGPOOL (MSGMNI * MSGMNB / 1024) /* size in kbytes of message pool */
 68 #define MSGTQL  MSGMNB            /* number of system message headers */
 69 #define MSGMAP  MSGMNB            /* number of entries in message map */
 70 #define MSGSSZ  16                /* message segment size */
 71 #define __MSGSEG ((MSGPOOL * 1024) / MSGSSZ) /* max no. of segments */
 72 #define MSGSEG (__MSGSEG <= 0xffff ? __MSGSEG : 0xffff)
 73 
 74 #ifdef __KERNEL__
 75 #include <linux/list.h>
 76 
 77 /* one msg_msg structure for each message */
 78 struct msg_msg {
 79         struct list_head m_list; 
 80         long  m_type;          
 81         int m_ts;           /* message text size */
 82         struct msg_msgseg* next;
 83         void *security;
 84         /* the actual message follows immediately */
 85 };
 86 
 87 /* one msq_queue structure for each present queue on the system */
 88 struct msg_queue {
 89         struct kern_ipc_perm q_perm;
 90         time_t q_stime;                 /* last msgsnd time */
 91         time_t q_rtime;                 /* last msgrcv time */
 92         time_t q_ctime;                 /* last change time */
 93         unsigned long q_cbytes;         /* current number of bytes on queue */
 94         unsigned long q_qnum;           /* number of messages in queue */
 95         unsigned long q_qbytes;         /* max number of bytes on queue */
 96         pid_t q_lspid;                  /* pid of last msgsnd */
 97         pid_t q_lrpid;                  /* last receive pid */
 98 
 99         struct list_head q_messages;
100         struct list_head q_receivers;
101         struct list_head q_senders;
102 };
103 
104 /* Helper routines for sys_msgsnd and sys_msgrcv */
105 extern long do_msgsnd(int msqid, long mtype, void __user *mtext,
106                         size_t msgsz, int msgflg);
107 extern long do_msgrcv(int msqid, long *pmtype, void __user *mtext,
108                         size_t msgsz, long msgtyp, int msgflg);
109 
110 #endif /* __KERNEL__ */
111 
112 #endif /* _LINUX_MSG_H */
113 
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