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Style changes:
- Move two IOCTL related defines to the top of the C-file - Add more comments describing the recently added IOCTL small size and small align macros
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=275205
@ -75,6 +75,20 @@ __FBSDID("$FreeBSD$");
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#include <security/audit/audit.h>
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/*
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* The following macro defines how many bytes will be allocated from
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* the stack instead of memory allocated when passing the IOCTL data
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* structures from userspace and to the kernel. Some IOCTLs having
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* small data structures are used very frequently and this small
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* buffer on the stack gives a significant speedup improvement for
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* those requests. The value of this define should be greater or equal
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* to 64 bytes and should also be power of two. The data structure is
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* currently hard-aligned to a 8-byte boundary on the stack. This
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* should currently be sufficient for all supported platforms.
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*/
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#define SYS_IOCTL_SMALL_SIZE 128 /* bytes */
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#define SYS_IOCTL_SMALL_ALIGN 8 /* bytes */
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int iosize_max_clamp = 0;
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SYSCTL_INT(_debug, OID_AUTO, iosize_max_clamp, CTLFLAG_RW,
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&iosize_max_clamp, 0, "Clamp max i/o size to INT_MAX");
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@ -646,10 +660,7 @@ struct ioctl_args {
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int
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sys_ioctl(struct thread *td, struct ioctl_args *uap)
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{
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#ifndef SYS_IOCTL_SMALL_SIZE
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#define SYS_IOCTL_SMALL_SIZE 128
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#endif
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u_char smalldata[SYS_IOCTL_SMALL_SIZE] __aligned(8);
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u_char smalldata[SYS_IOCTL_SMALL_SIZE] __aligned(SYS_IOCTL_SMALL_ALIGN);
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u_long com;
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int arg, error;
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u_int size;
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