Add macros around the sx operations in snp(4).
As an experiment, I changed snp(4) to use a mutex instead of an sx lock. We can't enable this right now, because Syscons still picks up Giant. It's nice to already have the framework there.
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=191999
@ -43,11 +43,22 @@ __FBSDID("$FreeBSD$");
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#include <sys/uio.h>
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static struct cdev *snp_dev;
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static MALLOC_DEFINE(M_SNP, "snp", "tty snoop device");
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/* XXX: should be mtx, but TTY can be locked by Giant. */
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#if 0
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static struct mtx snp_register_lock;
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MTX_SYSINIT(snp_register_lock, &snp_register_lock,
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"tty snoop registration", MTX_DEF);
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#define SNP_LOCK() mtx_lock(&snp_register_lock)
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#define SNP_UNLOCK() mtx_unlock(&snp_register_lock)
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#else
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static struct sx snp_register_lock;
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SX_SYSINIT(snp_register_lock, &snp_register_lock,
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"tty snoop registration");
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static MALLOC_DEFINE(M_SNP, "snp", "tty snoop device");
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#define SNP_LOCK() sx_xlock(&snp_register_lock)
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#define SNP_UNLOCK() sx_xunlock(&snp_register_lock)
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#endif
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/*
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* There is no need to have a big input buffer. In most typical setups,
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@ -241,14 +252,14 @@ snp_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags,
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switch (cmd) {
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case SNPSTTY:
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/* Bind TTY to snoop instance. */
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sx_xlock(&snp_register_lock);
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SNP_LOCK();
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if (ss->snp_tty != NULL) {
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sx_xunlock(&snp_register_lock);
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SNP_UNLOCK();
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return (EBUSY);
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}
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error = ttyhook_register(&ss->snp_tty, td->td_proc, *(int *)data,
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&snp_hook, ss);
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sx_xunlock(&snp_register_lock);
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SNP_UNLOCK();
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if (error != 0)
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return (error);
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