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Revision 4a23717a236b2ab31efb1651f586126789fc997f authored by Davidlohr Bueso on 13 December 2014, 00:54:30 UTC, committed by Linus Torvalds on 13 December 2014, 20:42:45 UTC 
uprobes: share the i_mmap_rwsem
 
Both register and unregister call build_map_info() in order to create the
list of mappings before installing or removing breakpoints for every mm
which maps file backed memory.  As such, there is no reason to hold the
i_mmap_rwsem exclusively, so share it and allow concurrent readers to
build the mapping data.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 3dec0ba
Raw File
encode_rs.c 
/*
 * lib/reed_solomon/encode_rs.c
 *
 * Overview:
 *   Generic Reed Solomon encoder / decoder library
 *
 * Copyright 2002, Phil Karn, KA9Q
 * May be used under the terms of the GNU General Public License (GPL)
 *
 * Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de)
 *
 * $Id: encode_rs.c,v 1.5 2005/11/07 11:14:59 gleixner Exp $
 *
 */

/* Generic data width independent code which is included by the
 * wrappers.
 * int encode_rsX (struct rs_control *rs, uintX_t *data, int len, uintY_t *par)
 */
{
	int i, j, pad;
	int nn = rs->nn;
	int nroots = rs->nroots;
	uint16_t *alpha_to = rs->alpha_to;
	uint16_t *index_of = rs->index_of;
	uint16_t *genpoly = rs->genpoly;
	uint16_t fb;
	uint16_t msk = (uint16_t) rs->nn;

	/* Check length parameter for validity */
	pad = nn - nroots - len;
	if (pad < 0 || pad >= nn)
		return -ERANGE;

	for (i = 0; i < len; i++) {
		fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]];
		/* feedback term is non-zero */
		if (fb != nn) {
			for (j = 1; j < nroots; j++) {
				par[j] ^= alpha_to[rs_modnn(rs, fb +
							 genpoly[nroots - j])];
			}
		}
		/* Shift */
		memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1));
		if (fb != nn) {
			par[nroots - 1] = alpha_to[rs_modnn(rs,
							    fb + genpoly[0])];
		} else {
			par[nroots - 1] = 0;
		}
	}
	return 0;
}
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