X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=kern%2Fsignal.c;h=5abd7062679aeacd91f085741c18db31e71d29f8;hb=2535cb94ec2183791128f8bbd109ca69a960cf78;hp=3e6fd1cbf725ba394a169325609516eb38648158;hpb=bcf38f772b397e7a8ba781a69aacb9380e54b32a;p=bertos.git diff --git a/kern/signal.c b/kern/signal.c old mode 100755 new mode 100644 index 3e6fd1cb..5abd7062 --- a/kern/signal.c +++ b/kern/signal.c @@ -1,9 +1,34 @@ /** * \file * * * \brief IPC signals implementation. @@ -18,6 +43,15 @@ * signals. POSIX signals are usually executed synchronously, like * software interrupts. * + * Signals are very low overhead. Using them exclusively to wait + * for multiple asynchronous events results in very simple dispatch + * logic with low processor and resource usage. + * + * The "event" module is a higher-level interface that can optionally + * deliver signals to processes. Messages provide even higher-level + * IPC services built on signals. Semaphore arbitration is also + * implemented using signals. + * * In this implementation, each process has a limited set of signal * bits (usually 32) and can wait for multiple signals at the same * time using sig_wait(). Signals can also be polled using sig_check(), @@ -33,96 +67,52 @@ * delivered twice before the process can notice. * * Any execution context, including an interrupt handler, can deliver - * a signal to a process using sig_signal(). Multiple distinct signals + * a signal to a process using sig_signal(). Multiple independent signals * may be delivered at once with a single invocation of sig_signal(), * although this is rarely useful. * + * \section signal_allocation Signal Allocation + * * There's no hardcoded mapping of specific events to signal bits. * The meaning of a particular signal bit is defined by an agreement * between the delivering entity and the receiving process. - * For instance, a terminal driver may be written to deliver + * For instance, a terminal driver may be designed to deliver * a signal bit called SIG_INT when it reads the CTRL-C sequence * from the keyboard, and a process may react to it by quitting. * - * The SIG_SINGLE bit is reserved for a special purpose (this is - * more a suggestion than a constraint). When a process wants - * wait for a single event on the fly, it needs not allocate a - * free signal from its pool. Instead, SIG_SINGLE can be used - * - * The "event" module is a higher-level interface that can optionally - * deliver signals to processes. Messages provide even higher-level - * IPC services built on signals. Semaphore arbitration is also - * implemented using signals. - * - * Signals are very low overhead. Using them exclusively to wait - * for multiple asynchronous events results in very simple dispatch - * logic with low processor and resource usage. + * \section sig_single SIG_SINGLE * + * The SIG_SINGLE bit is reserved as a convenient shortcut in those + * simple scenarios where a process needs to wait on just one event + * synchronously. By using SIG_SINGLE, there's no need to allocate + * a specific signal from the free pool. The constraints for safely + * accessing SIG_SINGLE are: + * - The process MUST sig_wait() exclusively on SIG_SINGLE + * - SIG_SIGNAL MUST NOT be left pending after use (sig_wait() will reset + * it automatically) + * - Do not sleep between starting the asynchronous task that will fire + * SIG_SINGLE, and the call to sig_wait(). + * - Do not call system functions that may implicitly sleep, such as + * timer_delayTickes(). * * \version $Id$ * * \author Bernardo Innocenti */ -/*#* - *#* $Log$ - *#* Revision 1.14 2006/07/19 12:56:27 bernie - *#* Convert to new Doxygen style. - *#* - *#* Revision 1.13 2006/02/24 01:17:05 bernie - *#* Update for new emulator. - *#* - *#* Revision 1.12 2005/11/04 16:20:02 bernie - *#* Fix reference to README.devlib in header. - *#* - *#* Revision 1.11 2005/04/11 19:10:28 bernie - *#* Include top-level headers from cfg/ subdir. - *#* - *#* Revision 1.10 2004/12/13 12:07:06 bernie - *#* DISABLE_IRQSAVE/ENABLE_IRQRESTORE: Convert to IRQ_SAVE_DISABLE/IRQ_RESTORE. - *#* - *#* Revision 1.9 2004/12/08 08:57:35 bernie - *#* Rename sigset_t to sigmask_t. - *#* - *#* Revision 1.8 2004/09/14 21:06:44 bernie - *#* Use debug.h instead of kdebug.h. - *#* - *#* Revision 1.7 2004/08/25 14:12:09 rasky - *#* Aggiornato il comment block dei log RCS - *#* - *#* Revision 1.6 2004/08/14 19:37:57 rasky - *#* Merge da SC: macros.h, pool.h, BIT_CHANGE, nome dei processi, etc. - *#* - *#* Revision 1.5 2004/08/04 21:50:33 bernie - *#* Add extensive documentation. - *#* - *#* Revision 1.4 2004/07/30 14:30:27 rasky - *#* Resa la sig_signal interrupt safe (con il nuovo scheduler IRQ-safe) - *#* Rimossa event_doIntr (ora inutile) e semplificata la logica delle macro con funzioni inline - *#* - *#* Revision 1.3 2004/07/30 14:24:16 rasky - *#* Task switching con salvataggio perfetto stato di interrupt (SR) - *#* Kernel monitor per dump informazioni su stack dei processi - *#* - *#* Revision 1.2 2004/06/03 11:27:09 bernie - *#* Add dual-license information. - *#* - *#* Revision 1.1 2004/05/23 17:27:00 bernie - *#* Import kern/ subdirectory. - *#* - *#*/ - #include "signal.h" +#include +#include #include #include -#include + #if CONFIG_KERN_SIGNALS /** * Check if any of the signals in \a sigs has occurred and clear them. - * Return the signals that have occurred. + * \return the signals that have occurred. */ sigmask_t sig_check(sigmask_t sigs) { @@ -140,7 +130,7 @@ sigmask_t sig_check(sigmask_t sigs) /** * Sleep until any of the signals in \a sigs occurs. - * Return the signal(s) that have awaked the process. + * \return the signal(s) that have awoken the process. */ sigmask_t sig_wait(sigmask_t sigs) { @@ -168,10 +158,40 @@ sigmask_t sig_wait(sigmask_t sigs) return result; } +/** + * Sleep until any of the signals in \a sigs or \a timeout ticks elapse. + * If the timeout elapse a SIG_TIMEOUT is added to the received signal(s). + * \return the signal(s) that have awoken the process. + * \note Caller must check return value to check which signal awoke the process. + */ +sigmask_t sig_waitTimeout(sigmask_t sigs, ticks_t timeout) +{ + Timer t; + sigmask_t res; + cpuflags_t flags; + + ASSERT(!sig_check(SIG_TIMEOUT)); + ASSERT(!(sigs & SIG_TIMEOUT)); + /* IRQ are needed to run timer */ + ASSERT(IRQ_ENABLED()); + + timer_set_event_signal(&t, proc_current(), SIG_TIMEOUT); + timer_setDelay(&t, timeout); + timer_add(&t); + res = sig_wait(SIG_TIMEOUT | sigs); + + IRQ_SAVE_DISABLE(flags); + /* Remove timer if sigs occur before timer signal */ + if (!(res & SIG_TIMEOUT) && !sig_check(SIG_TIMEOUT)) + timer_abort(&t); + IRQ_RESTORE(flags); + return res; +} + /** * Send the signals \a sigs to the process \a proc. - * The process will be awaken if it was waiting for any of them. + * The process will be awoken if it was waiting for any of them. * * \note This call is interrupt safe. */ @@ -183,7 +203,7 @@ void sig_signal(Process *proc, sigmask_t sigs) /* Set the signals */ proc->sig_recv |= sigs; - /* Check if process needs to be awaken */ + /* Check if process needs to be awoken */ if (proc->sig_recv & proc->sig_wait) { /* Wake up process and enqueue in ready list */