From 3ceadcf6d489650ade673b7197c11c521aecb038 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 3 Jul 2013 15:08:22 -0700 Subject: [PATCH] coredump: kill call_count, add core_name_size Imho, "atomic_t call_count" is ugly and should die. It buys nothing and in fact it can grow more than necessary, expand doesn't check if it was already incremented by another task. Kill it, and introduce "static int core_name_size" updated by expand_corename(). This is obviously racy too but harmless, and core_name_size never grows for no reason. We do not bother to to calculate the "right" new size, we simply do kmalloc(size_we_need) and use ksize() to rely on kmalloc_index's decision. Finally change format_corename() to use expand_corename(), krealloc(NULL) is fine. Signed-off-by: Oleg Nesterov Cc: Andi Kleen Cc: Colin Walters Cc: Denys Vlasenko Cc: Jiri Slaby Cc: Lennart Poettering Cc: Lucas De Marchi Acked-by: Neil Horman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/coredump.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 90d7cee..56a9ab9 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -45,26 +45,28 @@ #include int core_uses_pid; -char core_pattern[CORENAME_MAX_SIZE] = "core"; unsigned int core_pipe_limit; +char core_pattern[CORENAME_MAX_SIZE] = "core"; +static int core_name_size = CORENAME_MAX_SIZE; struct core_name { char *corename; int used, size; }; -static atomic_t call_count = ATOMIC_INIT(1); /* The maximal length of core_pattern is also specified in sysctl.c */ -static int expand_corename(struct core_name *cn) +static int expand_corename(struct core_name *cn, int size) { - int size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count); char *corename = krealloc(cn->corename, size, GFP_KERNEL); if (!corename) return -ENOMEM; - cn->size = size; + if (size > core_name_size) /* racy but harmless */ + core_name_size = size; + + cn->size = ksize(corename); cn->corename = corename; return 0; } @@ -81,7 +83,7 @@ again: return 0; } - if (!expand_corename(cn)) + if (!expand_corename(cn, cn->size + need - free + 1)) goto again; return -ENOMEM; @@ -160,9 +162,8 @@ static int format_corename(struct core_name *cn, struct coredump_params *cprm) int err = 0; cn->used = 0; - cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count); - cn->corename = kmalloc(cn->size, GFP_KERNEL); - if (!cn->corename) + cn->corename = NULL; + if (expand_corename(cn, core_name_size)) return -ENOMEM; /* Repeat as long as we have more pattern to process and more output -- 2.7.4