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| /freebsd-10.1-release/sys/kern/ | ||
| H A D | subr_devstat.c | diff 112368 Tue Mar 18 07:20:20 MST 2003 phk Make devstat fully Giant agnostic: Add a mutex and protect the allocation and traversal of the list with it. When we allocate a page for devstat use we drop the mutex and use M_WAITOK this is not nice, but under the given circumstances the best we can do. In the sysctl handler for returning the devstat entries we do not want to hold the mutex across copyout(9) calls, so we keep a very careful eye on the devstat_generation count, and abandon with EBUSY if it changes under our feet. Specifically test for BIO_WRITE, rather than default non-read,non-deletes as write. Make the default be DEVSTAT_NO_DATA. Add atomic increments of the sequence[01] fields so applications using the mmap'ed view stand a chance of detecting updates in progress. Reviewed by: ken |
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