23cfb71366
Even though we we had to abandon the master branch top multi-thread effort and even though the newlib version of a multi-threaded top provides no real benefit, that whole exercise was not wasted. Rather, it has revealed some deficiencies in our library which this addresses. If two or more threads in the same address space tried to access the same api simultaneously, there is a good chance some function-local static variables will yield some of those renowned unpredictable results. So, this patch protects them with the '__thread' storage class. Reference(s): https://www.freelists.org/post/procps/a-few-more-patches,7 Signed-off-by: Jim Warner <james.warner@comcast.net>
53 lines
1.5 KiB
C
53 lines
1.5 KiB
C
/*
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* wchan.c - kernel symbol handling
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* Copyright 1998-2003 by Albert Cahalan
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <stdio.h>
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#include <string.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include "wchan.h" // to verify prototype
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const char *lookup_wchan (int pid) {
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static __thread char buf[64];
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const char *ret = buf;
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ssize_t num;
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int fd;
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snprintf(buf, sizeof buf, "/proc/%d/wchan", pid);
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fd = open(buf, O_RDONLY);
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if (fd==-1) return "?";
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num = read(fd, buf, sizeof buf - 1);
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close(fd);
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if (num<1) return "?"; // allow for "0"
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buf[num] = '\0';
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if (buf[0]=='0' && buf[1]=='\0') return "-";
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// lame ppc64 has a '.' in front of every name
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if (*ret=='.') ret++;
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while(*ret=='_') ret++;
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return ret;
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}
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