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Set IPC status code only for RECEIVE

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This commit is contained in:
Cristiano Giuffrida
2010-04-26 14:43:59 +00:00
parent 5b0efc542f
commit 0f353411d7
2 changed files with 34 additions and 18 deletions
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26
kernel/ipc.h
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@@ -17,8 +17,28 @@
/* IPC status code macros. */
#define IPC_STATUS_REG bx
#define IPC_STATUS_GET(p) ((p)->p_reg.IPC_STATUS_REG)
#define IPC_STATUS_SET(p, m) ((p)->p_reg.IPC_STATUS_REG = m)
#define IPC_STATUS_CLEAR(p) IPC_STATUS_SET(p, 0)
#define IPC_STATUS_ADD(p, m) ((p)->p_reg.IPC_STATUS_REG |= m)
#define IPC_STATUS_CLEAR(p) ((p)->p_reg.IPC_STATUS_REG = 0)
/*
* XXX: the following check is used to set the status code only on RECEIVE.
* SENDREC is not currently atomic for user processes. A process can return
* from SENDREC in a different context than the original when a Posix signal
* handler gets executed. For this reason, it is not safe to manipulate
* the context (i.e. registers) when a process is blocked on a SENDREC.
* Unfortunately, avoiding setting the status code for SENDREC doesn't solve
* the problem entirely because in rare situations it is still necessary to
* override retreg dynamically (and possibly in a different context).
* A possible reliable solution is to improve our Posix signal handling
* implementation and guarantee SENDREC atomicity w.r.t. the process context.
*/
#define IPC_STATUS_ADD(p, m) do { \
if(!((p)->p_misc_flags & MF_REPLY_PEND)) { \
(p)->p_reg.IPC_STATUS_REG |= (m); \
} \
} while(0)
#define IPC_STATUS_ADD_CALL(p, call) \
IPC_STATUS_ADD(p, IPC_STATUS_CALL_TO(call))
#define IPC_STATUS_ADD_FLAGS(p, flags) \
IPC_STATUS_ADD(p, IPC_STATUS_FLAGS(flags))
#endif /* IPC_H */