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author | Dipankar Sarma <dipankar@in.ibm.com> | 2005-09-16 19:28:13 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-17 11:50:02 -0700 |
commit | 4fb3a53860cee2aaaf81186c451b7da0b95b45c1 (patch) | |
tree | db66ba7d3886644729707586aed781c445e12c16 | |
parent | af4e5a218e18ad588d60a4f9d6f8fb5db1a32587 (diff) | |
download | linux-4fb3a53860cee2aaaf81186c451b7da0b95b45c1.tar.gz linux-4fb3a53860cee2aaaf81186c451b7da0b95b45c1.tar.bz2 linux-4fb3a53860cee2aaaf81186c451b7da0b95b45c1.zip |
[PATCH] files: fix preemption issues
With the new fdtable locking rules, you have to protect fdtable with either
->file_lock or rcu_read_lock/unlock(). There are some places where we
aren't doing either. This patch fixes those places.
Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r-- | arch/alpha/kernel/osf_sys.c | 7 | ||||
-rw-r--r-- | arch/ia64/kernel/perfmon.c | 3 | ||||
-rw-r--r-- | fs/locks.c | 3 | ||||
-rw-r--r-- | fs/proc/array.c | 3 | ||||
-rw-r--r-- | kernel/exit.c | 6 |
5 files changed, 20 insertions, 2 deletions
diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c index 0636116210d2..01fe990d3e54 100644 --- a/arch/alpha/kernel/osf_sys.c +++ b/arch/alpha/kernel/osf_sys.c @@ -37,6 +37,7 @@ #include <linux/namei.h> #include <linux/uio.h> #include <linux/vfs.h> +#include <linux/rcupdate.h> #include <asm/fpu.h> #include <asm/io.h> @@ -975,6 +976,7 @@ osf_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp, long timeout; int ret = -EINVAL; struct fdtable *fdt; + int max_fdset; timeout = MAX_SCHEDULE_TIMEOUT; if (tvp) { @@ -996,8 +998,11 @@ osf_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp, } } + rcu_read_lock(); fdt = files_fdtable(current->files); - if (n < 0 || n > fdt->max_fdset) + max_fdset = fdt->max_fdset; + rcu_read_unlock(); + if (n < 0 || n > max_fdset) goto out_nofds; /* diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c index af42cda6be80..d71731ee5b61 100644 --- a/arch/ia64/kernel/perfmon.c +++ b/arch/ia64/kernel/perfmon.c @@ -2218,12 +2218,13 @@ static void pfm_free_fd(int fd, struct file *file) { struct files_struct *files = current->files; - struct fdtable *fdt = files_fdtable(files); + struct fdtable *fdt; /* * there ie no fd_uninstall(), so we do it here */ spin_lock(&files->file_lock); + fdt = files_fdtable(files); rcu_assign_pointer(fdt->fd[fd], NULL); spin_unlock(&files->file_lock); diff --git a/fs/locks.c b/fs/locks.c index c2c09b4798d6..f7daa5f48949 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -124,6 +124,7 @@ #include <linux/smp_lock.h> #include <linux/syscalls.h> #include <linux/time.h> +#include <linux/rcupdate.h> #include <asm/semaphore.h> #include <asm/uaccess.h> @@ -2205,6 +2206,7 @@ void steal_locks(fl_owner_t from) lock_kernel(); j = 0; + rcu_read_lock(); fdt = files_fdtable(files); for (;;) { unsigned long set; @@ -2222,6 +2224,7 @@ void steal_locks(fl_owner_t from) set >>= 1; } } + rcu_read_unlock(); unlock_kernel(); } EXPORT_SYMBOL(steal_locks); diff --git a/fs/proc/array.c b/fs/proc/array.c index d88d518d30f6..d84eecacbeaf 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -74,6 +74,7 @@ #include <linux/file.h> #include <linux/times.h> #include <linux/cpuset.h> +#include <linux/rcupdate.h> #include <asm/uaccess.h> #include <asm/pgtable.h> @@ -180,12 +181,14 @@ static inline char * task_state(struct task_struct *p, char *buffer) p->gid, p->egid, p->sgid, p->fsgid); read_unlock(&tasklist_lock); task_lock(p); + rcu_read_lock(); if (p->files) fdt = files_fdtable(p->files); buffer += sprintf(buffer, "FDSize:\t%d\n" "Groups:\t", fdt ? fdt->max_fds : 0); + rcu_read_unlock(); group_info = p->group_info; get_group_info(group_info); diff --git a/kernel/exit.c b/kernel/exit.c index 6d2089a1bce7..ee6d8b8abef5 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -371,6 +371,12 @@ static inline void close_files(struct files_struct * files) struct fdtable *fdt; j = 0; + + /* + * It is safe to dereference the fd table without RCU or + * ->file_lock because this is the last reference to the + * files structure. + */ fdt = files_fdtable(files); for (;;) { unsigned long set; |